Sorry.... I wasn't clear, I do that pretty often..
In my mind, I had those 5 men walking back to the base and turning into Tactical Marines. Or possibly, getting themselves killed, and turning up at the base as scouts and then upgrading themselves at the base.
Now, oviously, being able to upgrade yourself at your base, would be a slight cheese problem. Imagine attacking a base and preparing for scouts, only to find a bunch of
However, you could always just drop pod them in...
.
And, as for tanks and the like, I haven't given them any thought. 40k is all about the infantry, and, as such, tanks would be like end game units in the FPS, since, even the might bolter can only glance on the weakest of tanks (rhinos), it means that I expect tanks to be end game units... with Land Raiders and LRCs being very rare, while things like Dreadnoughts, Leman Russ (okay, lots of front, but side and rear are pretty weak), and perhaps a scattering of predators.
One thing I have vaguely thought of is HQ units, but this guys are soooo uber compared to normal men (multi-wounds). And of course, doing 'nids would be close to impossible. (imagine gaunts discussing tactics, and telling the Tyrant that he's stupid and should just let them assault... NOW!)