Mastering Questions (Digital Audio is like Magic, Right?)

A friend has asked me try and "fix" some audio tracks for a talk show she is producing for internet distribution.  I am a musician and composer who knows a little about mixing music, less about post-production sound, and virtually nothing about mastering.  I'm hoping some of you experts out there can give me some advice.
 
I have three DAWs I can choose from -  Sonar, Logic and Pro Tools.  My mixing tools/plug-ins/effects include the standard stuff included with these DAWs:  EQ, compression, multi-band compression, limiting, etc.
 
I've warned the producer that this is a "garbage-in/garbage-out" situation, the original audio was poorly recorded and has a lot of problems.
 
First, there are several places where the close mics cut out, leaving only the camera mics.  The audio from camera mics is clearly more muffled and has a lot more room reverb.  I've been asked to "fix this and make it all sound homogeneous" (!)  This seems to me like a mastering issue, and not something that can be fixed with my basic mixing tools above -- if it can be fixed at all.  Is there anything I can try using those basic tools?  Are there any mastering tools out there that a noob might be able to use to address this problem? 
 
Another issue is the hiss on most of the tracks.  I suspect this comes from a noisy mic preamp turned up too high.  The hiss is too broad-spectrum to treat with a notch filter.  I tried using a lowpass filter and I found that a cutoff point around 3.5k eliminates a good bit of the hiss without degrading the quality of the dialog too much.  Is there another approach that might be better?
 
Finally, on some episodes there is a noticeable difference in level between the host's voice and the guest's voice.  Both voices were recorded to the same track, so I can't just tweak the track levels.  I've used some basic compression to smooth things out somewhat, although you can still hear some difference between the two people talking.  Is there another approach to the problem?  Can someone give me some tips on the best way to use compression to deal with this specific issue?
 
Any advice you can give will be truly appreciated.  

It would have to be a very good friend before I'd even consider going near that project. You're looking at a lot of detail work that even an experienced post guy might have trouble bringing up to broadcast standards.
 
First thing I'd do is separate the two parts - with and without the main mic - into their own tracks. You'll have to EQ them separately in order to get them sounding similar. There are spectrum-matching plugins for just for that purpose, but they cost money. If there's no budget, you can still get there with the help of a good spectrum analyzer.
 
Next I'd apply volume automation to get the two voices to approximately the same level, and then compress the daylights out of everything.
 
There are tools that do a great job of hiss removal. You just have to give them a sample of the hiss in isolation for it to create a sonic signature from, and then let it go. No such tools come standard with any DAW that I know of, but the free Audacity editor has one. I haven't used that one myself, but I use Adobe Audition for such things and it does a remarkably good job of cleaning up such noise.
 
For de-reverbing you can try a gate and see how that goes. Another option is a transient shaper. SONAR's transient designer isn't very good but maybe Logic has a better one. Or if the producer is willing to foot the bill for a cheap plugin, grab either Meldaproduction's MTransient or eaReckon's TransReckon plugin. Both are currently on sale and both may be automated so that you're only suppressing ambiance during the parts where the main microphone has cut out.
 
No matter what, you're looking at a lot of tedious hand automation. Make sure the producer knows how much time you've put into it, because it's going to be substantial.

I can't add to what has already been said. It's a hard job to fix what was bad to start with.
 
This should be a lesson learned by your friend. Get it right the first time and you don't have these sort of problems.
 
I'd consider the first attempt a loss and simply move forward avoiding those mistakes again.
 
Help them attempt a fix if they need the first episodes for "posterity" and let it go at that.  It won't be anywhere close to broadcast quality but it is what it is.

What is your opinion of Izotope's RX3 plug-in (base and advanced)?  From their website it sounds like it might be useful in fixing some of these issues (may still require a lot of work).
 
I am weighing purchasing this or Adobe Audition to handle post production audio editing task and wonder which one will be more effective.

 
I use both Audition and RX3 advanced.  The tools in Audition are not nearly as advanced as RX, the latter is pretty much as good as it gets in the restoration world.  I only use Audition noise reduction tools for quick background noise elimination for radio broadcast.  
 
At any rate, like I said.  It is best for removing troublesome noise from already great sounding audio.  It won't make bad sound sound better.

"RX3 advanced... ...is pretty much as good as it gets in the restoration world."
 
I don't want to argue with Daniel but I think there is probably a very good reason why CEDAR hasn't had a need to discount their stuff so it competes on price with RX3. That stuff is black magic.
 
:-)
 

I would start be getting the SPL Deverb plugin and it is only $29 right now too. I would see how the sound from the camera mics end up after using this. It is not too much of an expense and it will come in handy for other things I am sure.
 
https://plugin-alliance.com/en/checkout.html
 
Here is some info on it too:
 
http://spl.info/produkte/...icroplugs/de-verb.html
 
If it does reduce the ambience on the camera mics then you could try using EQ to improve clarity.