Are you able to play online with TCs and other starcraft mods?
Yes and no. It depends on the software used to make them. Older mods that have not been updated within the year 2002 are probably using old technology that requires Brood War 1.07. With BW 1.07, you cannot use Battlenet, as it will try to upgrade your version. There are alternative solutions, such as the TPC and Aus-1 server. You can find the 1.07 connection files here. If you have multiple hard drives installed in your computer, be advised that people with them have been unable to get the connection files to work. Mods utilizing the latest technology, such as MPQDraft and MemGraft, are BW 1.09 compatible, and thus playable over Battlenet.