You’ve not really supplied enough information, and based on what you’ve asked, and how you’ve asked it, I would guess that you’re in unfamiliar territory. But to start with…
You don’t say where you are geographically – unless you go with a national carrier, it’s hard to predict, and even then, your mileage will vary. However, since you’re talking 40 locations, I’ll assume that you’re in a major metropolitan area. Cable modem access generally offers more “bang for the buck” in terms of bandwidth, but with some commercial exceptions (large ones) you are not allowed to get a fixed IP address, whereas with DSL you are. If you expect an income level to match, then T-1 or fractional T-3 can be more reliable and flexible, but it’s much more expensive in terms of monthly cost since those rates are typically tarrifed by the state public utilities commission. However, if you look at some of the alternate fiber optic installations (spotty), you can get a good deal that way.
In Q2 you ask about type of connections and use terms which really don’t belong together in terms of comparisons. VPN (Virtual Private Networking) means using the public networks, but encrypting all traffic so that it is unreadable. Private Networking means using one or more of a group of IP addresses (commonly referred to as RFC 1918) which are not route-able over the Internet – meaning that they are used strictly in private spaces, or tunneled through a VPN to another site. Neither of those has anything to do with the type of connection, which is mentioned above (Cable modem, DSL, T1/T3, satellite, rented fiber, etc.) Again, the type of connection is going to depend on what infrastructure is available at each of your locations. DSL (if offered) is primarily dependent on distance from the local telephone switching office. Cable modem (if offered) is dependent on where the cable company has chosen/granted permission to run their lines. Satellite is widely available, but the latency (round-trip time) is horrible. Rented fiber is completely dependent on where the fiber happens to be buried/strung, but sometimes they’ll run an extension for you. T-1/T-3 is almost universal, but is tarrifed at higher rates. For the long haul, frame relay may be cheaper.
Question3 deals with “re-distribute bandwidth”. This is NOT typical of anyone but an ISP. If you mean to take some bandwidth from one cafe, and give it to another, then you’re talking multiple ISP connections. If all of your locations are in one metropolitan area, then that might be doable by setting up a MAN (Metro Area Network) if you get a good deal from an alternate fiber vendor. There’s a LOT of dark fiber out there from the .COM boom/bust. But distributing bandwidth from one location to another requires that you have (or control) your own “backbone” network. You’re now also talking about some fairly expensive equipment, and the staff to manage it. Alternately you’re talking about crawling into bed with a large ISP that can DO that. Small ISPs don’t typically get
into that line of work. Better that you should re-think what you’re trying to accomplish.
I can’t answer Q4 – perhaps some other members have more information on this. My background is corporate networks.
Question 5 is self-limiting. If cost is not an issue, and you want to run at cheapest rates, I wonder how you’ll recoup your investment. I’d probably recommend that you get cable modem connections for customer’s speed/performance, and back that with a DSL with Fixed IP addresses, and tie your locations together with VPN’s for overall control.
One item that you did NOT mention was the machines themselves. I’ve had to deal with some “cafes” which had machines infested with keylogging malware which was collecting user’s credit card numbers and such. Kinko’s solved that problem by automatically re-imaging their machines every night – to keep them reasonably clean.