1- In the Run menu, toggle "Save .exe in the source folder". A small dot will be visible next to this when it's on. From now on, both F5 (compile and run) and ctrl-F5 (compile and run detached), as well as F11 (just compile) will output the .exe to the same folder where the .bas was loaded from.
2a- yes. 2b- no; there's no interpreter, only a compiler.
3- FILES will list the current working dir's files but won't let you handle the list. There's a custom function in the wiki that'll be useful to you: http://www.qb64.net/wiki/index.php/DIR$
. Also, while you're browsing the wiki, look for _CWD$ and CHDIR (return the current directory and change directories, respectively).
4- F1 when the cursor is on a keyword. Shift-F1 for general help. Info may be outdated, but pages can be updated in the Help menu. It's fetched from the wiki, though. Save that link to your bookmark bar
5- I run QB64 on an XP machine with only 1.5 GB of RAM. Give it a try.
6- There's a link around the forum with a tutorial on Android stuff. I'd say "it won't work, just stick to the desktop development". Don't be let down by my words, though. There are claims around that state the contrary.
But really it won't work. Android+QB64 is not a successful experiment.
I hope that helps.