Lots of good advice here. The kit lens isn't bad, but almost any set of primes will give better image quality. What the kit brings is flexibility and weather sealing.
Now, if you don't get the kit I think the DA21 would be a great companion to the DA50. The F/FA28 wouldn't be bad either (and a bit cheaper), I really like my FA. The reason why I won't recommend the DA35 is that it's a bit close to the 50 for a two-lens kit IMO. It's a very nice lens, though.
Actually, for me it would make more sense with a 21 + 35 (or 40) combo than the 50, but that all comes down to personal preferences and shooting style.
In the end, though, you might well end up like me, with all of the above - and then some