For host I believe you will have to get those that allow HYIP/Autosurf to be on their servers. To what I know not all allow that so you will have to take note on this.
Secondly is to consider the protection the host is able to provide for you, like anti-virus and anti DDOS etc.
Thirdly consider the bandwidth you will require. If you are just starting the bandwidth usage should not be too high but just in case your program grow to a stage where membership hit 10,000 or more you will need to get more bandwidth.
This are my 2 cents thoughts on what you should consider when getting a host for your hyip. Of because the list is still long but these 3 are what I felt most important when you are considering a host for your hyip.