3). For security purposes I am thinking of handling all orders manually from my cold storage vault and delivering within 24 hours, thoughts?
Seems good to me. The exchange I'm using delivers bitcoins twice a day. To me it never has been a problem. Be sure to create a FAQ on your future website with the withdrawal timing question.
4). I obviously don't know everything at the moment, so what major problems should I look out for when it comes to this?
5). What are your overall thoughts & concerns about this idea?
This kind of service could be really of good use for the community. I guess there is a lot of demand for this.
I guess your main problem will be to face chargeback (even on this forum a lot of people are "selling" credit card numbers), etc... It's quite a scammy situation for your project.
Second one is to be sure the security of your website is good enough. No body wants to give credit card informations and you will probably soon or later face hack attempts / DDOS attempts.
Be sure to find a law specialist before launching your project. You have to be sure of the tax your service will have to pay & think about a SIG campaign when you will launch your service. It will only work if enough people use it.
This seems this is going to be quite an expensive startup, I am thinking of offering cash deposit payments & wire transfers. Because they are secure & and I can send bitcoin orders out quicker too because I would just have to verify the deposit in my bank account.