24 yo is not too late to start.
1. It depends on what you want to do as well as the employment market when you finish. Can you afford to do a degree and then finance an integrated course? Depending on the market, you could work for 2 years, save up some cash and then go full time? Only you know your financial state.
2. It was pretty rife a while ago but it seems to have eased as pilot numbers have dwindled. I'd still think about having that money tucked away.
3. Some countries have dropped the national language requirement, but most still have it. Ideally, the more suitable experience you have the easier it is to get around such things. As a low houred pilot, the Middle East probably won't look at you. As with any employer, it depends. I don't know the German language fluency requirements. It's probably on the Lufthansa site.
4. Don't know. Haven't looked.
5. Don't know. Haven't done it. I fly a private jet. Others will know. An example. BA B777. LHR to Male (Maldives). Cabin crew got 3 days. Pilots got 14 hours. Just how much sight seeing do you think they got? When you're young, your recovery time is amazing, +50yo? You just want sleep in your own bed.
6. Some don't. There are contracts and there are contracts. Once you have relationships/family. Being home appeals. Depending on the relationship, being away for a month sounds good.
7. Freight dog life. I did parcel pup flying. It's fun but knackering. DHL do take non Germans. I have a couple of Belgian colleagues who flew for DHL. The money being offered in the US for freight dogs is eye wateringly incredible. Not so much for DHL in Europe. An FO at NetJets Europe earns more than a DHL EU captain.
Hope this helps.