1- the gas starts at center and when pressed goes "up" joystick- is that ok? does it matter?
That's fine. The pedal will be calibrated in-game.
Most PC games default to gas and brake being different sides of a single axis.
Unfortunately Model 2 emulator requires they be on separate axis, so keep that in mind.
2. are there any games that use analog break and/or analog clutch
Some games are downright unplayable without an analog brake.
Few games had a clutch. Of the ones that did, only a few couple were analog (Hard Drivin', Race Driving, SF Rush).
That said, if you've got an input on the apac for it, there's no reason not to make it analog.
3. After all this do I use joytokey or padder
to just make the analog brake and clutch to pushbuttons for most things?
Most things can accept the analog input. I have both a pot and switch on my clutch pedal.
My hacked Logitech wheel pcb only has inputs for 2 pedals, so I had the clutch on a separate input device.
That caused issues, so I went to just using the switch.
4. Is the gas pedal ok for mame? is there
any other racing games/ programs that use analog for gas?
Pretty much everything requiring a gas pedal requires an analog one.
Even if it doesn't, the analog will work fine with it.
Here is a spreadsheet of driving games in MAME and the type of controls they used.
https://docs.google.com/spreadsheet/ccc?key=0Aq37CSO6oe1fdERrVGt0emFCWnh1WDBiaFdoUmcweHc&usp=sharing#gid=0Take the time to read the stickied Driving Cab info thread at the top of this forum.