Welcome! You chose a fun class. Now on to your questions.
- Weapons: Gosh, honestly most monks are twinked on this server. Just use what you can for now and save up for Fighting Batons (8/20). They are not unreasonably priced, but obviously out of your range for now (600pp?)
- Weight: For the most part, the weight penalty should be ignored under lvl 20. Loot up what you can to save up for that fighting baton.
- Mend: at 100 it works every time. Do NOT use it in combat until you get it pretty high. And when traveling or anything non-combat, still click it for the skill up chance.
Good luck and hope you enjoy it!