I'd also like to learn more about SBS and other servers in general, although I wonder if this act will throw red flags for a home ISP. I'm not trying to violate any TOS, although I'd really like to learn more and you can only go so far in SBS 2008 without an external domain (RWW, etc). It isn't about hosting the domain so much as learning about what SBS 2008 is capable of.
Internet issues with a mail server (like SBS 2008's Exchange Server) will depend on your ISP and the type of account you have. With Home-level Internet accounts, there may be rules or actual blocks of TCP Port 25 inbound or outbound. Sometimes firewall blocks can be worked around using the ISP's smarthost services (if they exist).
There may be inbound blocks on TCP Port 80, also, to prevent hosting public web sites. If the sites are for your own use, you can change ports or use TCP Port 443 or can use IP services like No-IP.com. Some ISPs do allow mail servers or web sites. Some have rules against them but don't enforce the rules unless they are massively violated.
SBS' remote access likely won't be affected by your ISP. I've never heard of any that block TCP 443, TCP 3389, or TCP 4125. SBS' internal features, Exchange itself, SharePoint, the Domain Controller function and the DNS and DHCP functions won't be affected.