[jacquesm]

If you are in the US and your target market is the US then for sure you should limit your search to IPSPs in your country, there would simply be too much hassle getting set up elsewhere.

I'm not sure if authorize.net will allow you to plug in your own merchant account.

The reason why that is important is that the chance of the IPSP going under or being fined some massive fine are diminished substantially if you have your own merchant account.

See 'IBill' and 'DMR' for what can happen if you decide to use a multiplexed account, plenty of people lost their shirt or worse.

Another risk is that your 'good' traffic will be used to dilute 'bad' traffic in order to lower the charge-back rate on the bad traffic as perceived by the card companies.

The pre-auth feature should be offered by most gateways I don't expect any major problems there unless your period is longer than the 3 to 5 days indicated above.

Longer than that and it is probably better to simply charge the account right away and do a whole or partial refund.