Hi,
Welcome to Germany, and to the forum!
Your worries are pretty common before a big move, but there are solutions for everything!
1. Is it a good idea to rent in Stuttgart and commute (approx. 45 minutes with a train) to another city? Are the trains reliable? Is it troublesome in winter (e.g. issues on rails etc.)?
Trains are generally (but not always) on time, but you need to consider the complete (door to door) journey, which is likely to be much longer than just the train ride. Also, the ticket cost and higher rent in Stuttgart might add up. The decision is yours, but I would prefer to stay at Heilbronn.
2. What is the procedure for apartment rental usually like? I do realize there are differences between the agencies/owners etc. but generally speaking:
- Is it AT ALL possible to rent a place before you actually come to Stuttgart (e.g. how likely is it I will be scammed/ nobody will want to rent their place without meeting me/ nobody will rent a place to me because I am Polish and have no working/living/credit history in Germany)? I have read that owners request crazy amount of paper work (e.g. proof of receiving salary in a few months, credit report, references) - is that true?
The procedure, preferences and required papers very much depend on individual landlords and can range from very easy to extremely buerocratic. Discrimination based on nationality is not allowed, but of course happens.
It is difficult to find anything before you arrive, so I always recommend to book temporary accommodation for the first weeks and seach when you're here. That way, you can see what you rent and are less likely to fall for scams.
- What is an acceptable price? I have seen sources mentioning some approximate prices but then I saw listings for really crappy appartments for approx 1000 euro per month and some for 500 looking pretty good - is this too good to be true? Also, is craigslist reliable? Did anyone use it to find an apartment?
Craigslist is not common here. Use quoka.de, kleinanzeigen.ebay.de or immoscout24.de.
There are official surveys of rental levels, called "Mietspiegel", for each city. But in the end the price depends on supply and demand. So ask yourself how much you want to pay and where you are willing to compromise (on location, convenience, luxuries, etc.).
- How are payments made? I would imagine I won't hand over any money until I get my keys or the contract... I tried to rent a "business apartment" but the owner insisted I pay almost 2000 euro upfront for a tiny flat (and security deposit) before he even signed the contract with me. My company agreed to pay for my flat for a few months; if I request an invoice do I still have to pay upfront? In Poland when one gets an invoice it is handed to the company and there is approx. 2 weeks for payment. Is it similar in Germany?
All deposit and rental payments are done by bank transfer, after the rental contract is signed and valid. Do not hand over any money before a contract is signed - that is a sure scam!
3. Is it a good idea to ask my employer to rent a place for me instead of reimbursing my rent costs? That is, is it a common practice to ask your employer to sign a lease in their name and handle the entire thing? I don't want to be a burden, since they are already paying for my travel costs and apartment...
This is not common, but if your employer agrees to it, it is a good idea!