Upgrade 600HD or new 1200

[SidVicious]

Right now i got one Amiga 600HD and one Amiga 500.I have found a chip that gives the Amiga 600HD 1mb extra fast RAM (2mb total). It would cost me around 36,49USD.
 
Anyway, i have found one Amiga 1200 and a 1942 monitor for around 145,94USD. The problem is...

Right now i only use the Amiga 600HD for transfering ADF games to floppies.

1. Workbench is low as hell right know. How slow is it on Amiga 1200 without HD? (Workbench 3.1), and, how much does 1mb fast ram speed up the Amiga 600HD?

2. Is it possible to install a Graphic card in the Amiga 1200HD without changing the case to a tower case?

3. Is it hard to install a HD in the Amiga 1200?

4. Is it possible to use a more highres then on the Amiga 600 mode on the Amiga 1200 whithout flickering on the 1942 monitor?

omfg, my english sucks realy! Sorry for that, if you don't understand something...just ask.

[SidVicious]

Oh, thx for the fast awnsers! =)
Ithere anyway to use a higher screen res without e scandubbler/flickerfixer and a VGA/SVGA monitor?
The work area in Workbench 2.05 feels too small. =(
I always runing thing in windows so they don't use the whole screen...right know i only have place for 3 CLI windows...and that isn't much.