Forgotten passcode / backup / device restore

I forgot my old iPad 2 (from 2011) pass code. I’ve used two attempts so far and then stopped trying for fear of making the situation worse.

I have a backup of this iPad from about 3 years ago, but I’d like to know the following:

1) Can I perform a backup now without the passcode via iTunes? What I mean by this is having the latest possible backup, so remembering the passcode stops being an issue. In the past, this iPad has been trusted in the iTunes of the MBP I'm currently using, so I guess it's something to consider.

2) If the answer is yes and I proceed to restore the iPad afterwards, will it still require me the old passcode? I know this question sounds weird because the idea is to skip the old passcode, but I've never restored a device before, so I really don't know how it works.

3) What backup is more complete, the one done locally or the iCloud option?

4) If I turn off the iPad does it reset the number of failed attempts?

5) Assuming I can create a fresh backup, can I use this backup and restore it to a different iPad?

6) Does a backup contain literally everything or do some of the files get erased?

To clarify, it’s an iPad 2, running iOS 7.11

Thanks for taking the time with this thread.

I appreciate any help along the way.