Upgrade OS 10.5.8 to Snow Leopard - any problems?

My computer info:

Model Identifier: iMac8,1

Mac OS X Version 10.5.8

Processor: 2.8 GHz Intel Core 2 Duo

Memory: 2 GB 800 MHz DDR2 SDRAM

Number Of Processors: 1

Total Number Of Cores: 2

L2 Cache: 6 MB

Memory: 2 GB

Bus Speed: 1.07 GHz

Boot ROM Version: IM81.00C1.B00

SMC Version (system): 1.30f1

I've been happy with my OS X 10.5.8, but I'm getting messages that my Safari Version 5.0.6 browser will no longer be supported by various web sites and Google Mail. I can't upgrade my browser unless I upgrade my OS.

I guess I'll have move into the 21st Century!

I don't use any apps like Blue Tooth, Cell Phone, etc. but I do use Airport for connecting to the internet.

My questions for you tech wizards:

- If I purchase and install Snow Leopard, will I lose anything I already have on my computer: files, photos, software, etc?

- Will I still be able to keep Photoshop Version 8.0 or will it disappear? I don't have the disk to reinstall it.

- How difficult would it be to upgrade Safari and Firefox after Snow Leopard?

Thanks for any help for this "in the stone age" computerist.

Nina