i notice that my maximum available/free memory (from sbs toggle) is at 267MB. using apps one on top of the other reduces this. the value also changes while i'm working within an application.
does a small amount of free memory lead to freezing or soft reset of the iPad? sometimes, i'm in the middle of doing something important then everything stopped, ruining my work...
is there a threshold where i shouldn't open any more app to avoid freezing/soft reset? is there an app to notify me if memory is running too low?
is there a way to increase the total memory? double or treble the original?
i don't want to experience that again...
The easy one out of the way - no, there's no way to increase that memory (that's the RAM and you can't add more to the iPad).
For the other: When I am going to run an app that I know is a RAM hog, I'll run Remove Background (Cydia app) first. Then, sometimes I'll also run XSysInfo (App Store app). This clears up a lot of the in-use RAM. That's usually enough to get me through a session with the RAM hog.
Of course, you can run a reboot - but the two options above are easier and faster...
Also, running a lot of Cydia tweaks uses up RAM. Take a look in your "More" section in SBSettings. At the bottom is a line "Mobile Substrate Addons." If you take a look, all those that are running are eating up your RAM.
Now, I DO NOT recommend turning off any of those Mobile Substrate items! But, if you still have crashing while running an app after removing all others from the background, you may want to consider putting your iPad into Safe Mode for the duration of your app use. This will turn off those Mobile Substrate items, which will free up a whole bunch of RAM. Then, when you are done with the app, just restart and you are back to "normal."
That's the only suggestions I have for you. Oh, there's one more. You can always remove some of the tweaks on your iPad. The less tweaks you run (usually, the ones with the drill-looking icon), the less your RAM is affected.
Hope that helps.
Who really doesn't have any sympathy with a person talking of RAM issues with an iPad2 - twice that of the iPad1. :D