not op but
1 runs in both
2 i was told "use best" or "most profitable" was only for restocking, which is not currently enabled
3 they are not
4 no, it will not. if you pick herb runs at level 1farming, it will get stuck trying to withdraw seeds for your level -- regardless of whether or not "highest level" or "most profitable" is checked. minimum level for herbs is 9, so i would suggest doing potatoes until 9 then you can do herb, flower and vegetable patches no problem.
5 only works with regular teletabs (camelot, falador, etc) cannot use runes to teleport -- this is as far as i know since i don't have a portal nexus.