NMTeaco -

I just got into bitcoins myself a few months ago, so I can appreciate your current position on the learning curve.

I'd say that YES the blockchain.info wallet would be a great solution for your needs. All of the encryption & decryption is done locally on your machine and the operators of the site do not have access to your coins. Additionally, they email you encrypted wallet backup keys so if one day the blockchain.info site disappears you can still restore your bitcoins into another wallet.

Blockchain.info has a support/development thread on this site that is dozens of pages long and where they have provided plenty of details of their security measures and have satisfied this (very demanding) community.

For someone with your transaction volume, I think it's a no brainer to use their wallet and make periodic deposits on an exchange or do an OTC exchange via a trusted forum member where they send you a personal check and you send them bitcoins. The only other thing to remember is to NEVER forget or lose your blockchain.info wallet password as they cannot recover it. That goes hand in hand with the admins not having access to your coins.

Honestly, I don't really trust any exchanges very much and only leave assets on an exchange for as little time as possible.

Bitfloor was one man show run by a 25 year old guy with experience as a programmer, but no real business experience. He was grossing about $2500/month and living in New York City while being responsible for  $300k or more in assets. I don't see how he could afford to eat, let alone pay for security audits and the like, so the Bitfloor hack was a foreseeable disaster waiting to happen.

Edit: What jwzguy said above me is correct. He's just not as verbose as I am.