Tomato problems:
Suppressing side shoots and “stopping out” will help to control the size of your overall plant.  Use jute string (it’s hairy and sort of sticky) and try a better knot (www.animatedknots.com ) such as clove hitch. Regular feeding and watering is essential for a good crop, and I would recommend any generic tomato feed.

Mint rust: 
Dig up any affected plants and get rid of them, not on the compost.  If the mint is in a container, you should probably change the soil and scrub out the container as well.

Fruit varieties for 650m altitude:
Look out for late-flowering forms for any fruit.
Zeva or Malling Promise for raspberries.
Andega or Géant de Boskoop for blackcurrants.
Redstart or Rovada for redcurrants.
Brown Turkey is probably the best bet for figs, but it’s risky because of the risk of freezing.
Cerise de Montmorency or Belle Magnifique for cherries.
Apples are tricky if you only have space for one tree, as all apples need at least one other tree that flowers at the same time (known as a pollination partner.) The solution is to find another tree locally (talk to your neighbours) and match your new tree’s flowering time to theirs—time for a bit of detective work!