How do I fix and prevent this rust on the front wheel?
The rust shown is purely cosmetic.
Rust removal / Cleaning needs to be done with care. Even with the rubber seal, theres a chance of getting contamination into the bearings. I would use a small wire brush and gently take the worst of off, then spray the surfaces with WD40, a silicon spray or other water repealant/lube spray. Not too much as you don't want it in the bearings. Oil or grease can also be used but be careful not to leave too much on - apply and wipe with cloth to remove excess.
If the bike is stored outside or in a damp location you may want give the metal surfaces a quick squirt regularly- especially after washing the bike.
You could buy something like ACF-50. It isn't cheap, but if you put some on your bike every year or so with a cloth, it gets into the metal and helps protect it and one can should last quite a while.
Put it on your bike after you have washed and dried it.
By the way, please don't put oil, WD-40 or anything like this near your brakes - especially if you have discs.