List of essential tools to maintain an Ortler Mainau bicycle We have three Ortler Mainau bicycles in our family that I would like to maintain. We don't have a garage but only a smallish cellar, and I would like to work there (e.g. I cannot use toxic things there).

The maintenance tasks I would like to do in short term:
  - Adjust the breaks/gear/seat post/etc. as it is necessary.
  - Regularly clean the chains
  - Fix a flat tire

The tasks I would like to do medium term (if I need):
  - Fix a slightly warped and twisted wheel
  - Fix the lightting
  - Rewire the breaks/gears if it is necessery

I have no tools at all, so my question is that what tools I have to buy in order to be able to maintain those bikes in short term?

I live in Switzerland close to the Alps so the weather is quite wet (e.g. I assume that I need different oil for wet weather than for dry weather).

Thank you in advance!

(Updated according to the admin requirements)
Lennard Zinn has written books on maintaining road and mountain bikes (a trekking bike probably falls under the "road bike" category in terms of maintenance). He lists four levels of tool kits based on how ambitious you want to get with servicing your bike. I think this is a reasonable approach, especially since we don't know how ambitious you want to get servicing your bikes in particular.

Also, to some extent, a tool's necessity will be determined by what kind of bike you have, for instance, my road bike has no torx bolts; with a carbon bike, a torque wrench is probably more important. So any advice also needs to be tempered by the bike you're servicing.