I've got no idea about using the monitor with the travel cot, but personally I don't think a travel cot should be used all the time for baby. I am using one currently downstairs, so I can just pop baby in, instead of running up and down the stairs all the time. My bub is 3 weeks old now. I have a problem with the sturdiness of the cots.
For short term use, I think they are fine, but for long term I think something stronger should be used. I only have this concern, because in the last 2 days, one of the sides of my cot has disengaged twice, both times when baby was being attended to in the cot. It may have been the pressure of one of us slightly leaning on the side to reach bub, but it scared me. I was under the impression it was supposed to be more secure...maybe we just bought a dud!
Saying that though, my 5 year old used a travel cot quite frequently when she stayed at Nana's place, and we never had a problem with it. So as long as it's sturdy, it should be fine I guess.
Sorry I'm probably not much help. Your post just seemed relevant to my situation the last few days!
3 girls are enough...the shop is now shut!