-- Is it possible/hard/easy/trivial to share the load between the two connections? Have either link fail and things still work correctly?
http://en.wikipedia.org/wiki/Autonomous_system_(Internet)
Two connections from two different ISPs? You need a ASN. (not for load sharing...this is primarily to handle link failures)
-- What are the implications of two pipes for incoming connections such as DynDNS based remote desktop or VNC, or web server, FTP, etc
Incoming connections will hit either IP and use that IP for the duration of the connection provided that you have a DNS entry that round robins...
The basic hardware layout I see is 3 nics, 1 GB RAM, 60 GB disk space. 1 NIC for each WAN port, 1 NIC for my local net, some recent CPU.
I have been browsing through the “Linux Advanced Routing & Traffic Control HOWTO,” but am still not on top of how to get done what I’m looking for. I understand that there are probably products that I could buy to do this, but my preference is to do it myself.
I do have a box that has two connections from two different ips. I basically forget about load sharing. I setup multiple routing tables, some ip rules and basically assigned one link for vpn and server activity while the other link is used for office Internet connectivity and a few small things are shared like DNS. Nothing fancy...