Question about Hamburg:-
1) What is the public transport like in the city
2) Is the tennis far from the main city?
The public transport in Hamburg is very good! You can take the metro almost everywhere (and there is a metro station directly at the tennis venue, the station is "Hallerstraße"). Apart from that, there are also busses (for example, if you want to see a bit of the city as well), but I would prefer metro, it is the best and fastest way.
Here is a link to the metro plan of Hamburg:
There you also see that the tennis is very central and close to the central station (it is on the blue line U1). I would say it is max. 5-10 minutes from the city by metro to the tennis
So very close
If you have more questions, feel free to ask
Btw, quite funny...I was also in Monte Carlo last week
Though I must admit I already had better weather there than this year