Dedicated Server Applications for Sending Bitcoins

Hello all,

Please accept my apologies if this has been covered; I have spent a good deal of time researching this, and I have not been able to find an answer.

I am developing a website, and I've currently got two tricky requirements:
1) Must be able to send bitcoins to another address (without manual intervention)
2) Must be able to store the wallet file itself (in other words: no reliance on someone else to manage the wallet)

First question: do I need the entire database of blocks in order to construct valid send transactions? I think the answer is "no," which leads into my next question.

I know I can use JSON RPC calls with bitcoind; however, I am concerned that the downloading of blocks may not be economical, because I will need a dedicated server with a fair amount of resources. Second question: is my concern valid?

Finally: if my concern is valid, is there an application which will enable me to create valid send transactions without actually downloading the blocks?

Thanks