Q1.
a. Only in certain areas, you should notice faster boot times as well as faster application startup. Now in certain software you will not see a full difference, it might be about a second faster load time in a game for example. But it all depends what you are doing on the laptop. Since you are not gaming and mainly focused on those applications running better, then an SSD won't do much to help the actual application do it's job. A CPU upgrade would help more in that area.
b. Depends on your price range and how much space you're looking for, you should read a little about the differenct SSD's. Here is an SSD hierarchy here at Toms Hardware:
http://www.tomshardware.com/reviews/ssd-review-benchmar...
c. There shouldn't be, but no one can predict such a thing. If the laptop has a SATA interface you should be able to slide an SSD in there and throw an OS on it and everything should be fine. Make sure you have AHCI mode enabled as well.
Q2.
a. Make sure you can remove the CPU first off. A a lot of laptops have the CPU integrated into the motherboard. If you can change it up then the highest you can go may be a T9600, but there are other Penyrn Core 2 Duo chips that perform better then that (Core 2 Extreme chips). But you just need to check online and do some research to see if the X9000/X9100 chips are supported.
b. That is dependent on what you do with the system, upgrading a certain component in a system doesn't nessicarily mean overall performance gets better. You'll just get better performance out of the software that utilizes that/those new components. If i upgrade my GPU and i don't game or do anything that uses the new GPU then no, performance will stay the same.
c. Yes, as mentioned, if you didn't check the CPU might be soldered onto the motherboard. Also you might need a BIOS update depending on the CPU you get. As you might be running an older BIOS that has not been updated for better Penryn chips. Problems can always occur when swapping parts, but we can not predict all of them that could arise.
Q3.
a.Again, this depends on what you need to get done. Those two parts are not parallel comparisions, as upgrading to an SSD will see a performance benefit in a different area then a CPU upgrade. I say that if you don't do much to any gaming as you say then an SSD upgrade would probably be the best thing for you. If you were to do a bit of gaming and/or run CPU dependent software like photoshop, VMware etc. then a CPU upgrade might be best.
Q4.
a. I'd upgrade the the CPU if you want those certain applications like VMware to run better. But the only reall option you can upgrade to is the X9000/X9100 chips, as you already have a T9400 and the highest you can go on the C2D's are the T9600's.