Wrat,
If you pump for extended periods of time, the lymph fluid that is "sucked" into your penis can sometimes make it sort of lumpy looking. It's especially noticeable an hour or so afterward when you're soft. This has always gone down for me, though and eventually just leaves me with a normal, though thicker and heavier cock.
Even when I wake up the next morning with it feels thicker and more meaty than on days I don't pump.
I don't EXPECT a permanent increase in size, but it'd be nice. And the temporary increase seems to last a lot longer than the word temporary would suggest.
Re: erection
Because the swollen tissue is caused mainly by lymph fluid, yeah, the ourside of your erection can be a but spongy and soft, versus the rock hard feeling of a plain ol' woody. No complaints from the little lady on the new and different feeling. It's fun to watch her eyes get really big when I put it in her though, and then she says "more lube" The intensity of my erection hasn't been affected thus far.
Re: sensitivity
I've noticed both and increase in sensitivity, and a decrease. I know that doesn't make sense, but it's true for me at least. I can have sex for just as long with it pumped, so I wouldn't worry about that.