hey @ATourist,
thanks for posting 
to give you some quick first-approximation-answers:
- just turned 30
age is the least important factor to decide for or against 3a pillar. unless you are chasing the last bit of performance, I think generally you cannot be wrong with 3a-Investing. As long as you have not fully made up your mind, I recommend you to max out a 3a with a simple savings account to benefit from the tax excemption. you can then at a later point (better sooner than later, lets say within a year) decide what to do with this money within 3a. Keep in mind you cannot easily get it out of the 3a framework, but shift it between 3a products.
- ETFs/stocks etc. of my choice. So I still need to pick out these things?
Yes and no. Yes because ther are products that allow you to pick ETFs out of a (quite small) basket. You find more about this in this thread. No because the “yes case” is rather exceptional today, so most 3a stock based solutions (that are considered by mustachians) let you buy a fund of funds with given allocation of underlying funds, so your coice is more “pick a risk level between 1 and 5” rather than on individual assets. In both cases monthly paiments are usually applicable.
- UBS
Since UBS in general is expensive, the mustachian consensus is to move avay to less expensive banks. This mostly holds for theiy 3a funds, but i never looked it up in detail. so no advice from my side here
- Any advice on how to start out?
yes: first take some time and read up on the topic “passive indexing for private investors” until you have a clear picture on the whole thing. find some recources here. Once you have a clear picture on what your long term strategy is, set up an account with some broker (you find a couple of threads in this forum about this topic) and execute it.
normal low cost brokers require you to do the transactions yourself, which (in case of a montly occurence) might conflict with the idea to keep transactions costs low. If you don’t want to be involved other than a monthly wire transfer, a robo advisor (Truewealth) might be interesting for you.