Sound Center: Some basic questions

Hello everyone,
I am not using synthesizers a lot but every now and then I like to spice up my recording with a little extra non analog instrument here and there. For this I like Sound Center. Although it is rather simple I still haven't fully understood certain points. I checked the main SONAR help and the included web help but still have these very basic questions (if I simply overlooked some help files just refer me to them):   
 
Here we go:
Basically I just want to add different Sound Center instruments to different parts of a song.
Now, very simply:
1) Do I have to load different instances of Sound Center for each instrument I am using?
I was looking for some way to have different midi files and then somehow address a specific Sound Center instrument with midi file 1 and another instrument with midi file 2. Is there anything like that or is it one instrument = one Sound Center instance?
 
Similiar to that:
2) Can Sound Center be automated somehow? Can I have one instance of Sound Center that plays instrument A during bar 1 to 10 and then changes to another instrument on bar 11?
 
Now, this is a bit more far-fetched and not so important:
Before using Sound Center I was using midi sounds with the Standard Windows Midi player. I changed to Sound Center because I didn't find an easy way to transform these midi files into audio. The only method I found was solo the parts, play them and then record externally with audacity and reinclude the recorded file back into SONAR.
3) Is there a better way to do that? Seems like I should find some kind of "Record what you hear" option but I didn't.
 
Again, even if some of that sounds idiotically simple to some getting some hints and explanation would be really helpful for me. 
 
Happy greetz
Steffen

It is possible to send program change messages via MIDI to a VSTi, I think, as you would with an external synth, but I find it easier to create an instance of whatever VSTi for every instrument/track I need. It's just easier that way, in my opinion.
 
As Grem says, freezing a synth is the best way to go, and is another reason why it would be easier/better to have an instance of sound center for each instrument you require.
 
cheers
 
andy

@scook: Thanks for mentioning "Microsoft GS Wavetable Synth". I couldn't remember the name. This is what I meant with "Standard Windows Midi player". 
 
Is it correct that unlike other soft synth the Microsoft GS Wavetable Synth does NOT allow to freeze or bounce a track? That is how it seemed to me and that is the problem I tried to explain at 3) of my initial posting.
 
By the way, can someone explain what the Microsoft GS Wavetable Synth exactly is? 
It is always there, unlike other soft synth it does not have an interface, just allows me to send my midi files to one hundred something standard midi sounds. Afterwards I can hear these midi files played with the sound of the chosen instrument, but there is no way to freeze or bounce it.

Thanks a lot, scook. That helped understanding and also is a great practical tip.