Do heat sinks/multi-hack mods work on enemy portals?

Solution 1:

Yes, you will :)

Mods efficiency is not "faction related", a "great" (high level, good mods) portal will be great for everyone.

Yes, you would get the same benefit from the portal mods as someone from the other faction that was hacking the portal.

There are definitely good reasons to hack enemy portals, such as:

if you're in need of items and the nearest friendly portal is far away
if you're in need of AP (since you get 100 AP per hack)
if you're in need of high level items and the enemy portal is a higher level than you could get it to by deploying your resonators on it

Keep in mind though, it doesn't always make sense to hack enemy portals since:

sometimes you won't receive any items from a hack and then you've used XM to hack it for nothing
enemy portals zap you of your XM based on the table below

Portal Level | Damage If It Zaps You

1 | 75

2 | 125

3 | 175

4 | 238

5 | 300

6 | 400

7 | 500

8 | 600