Yes.
The lane that goes to the resort goes to the resorts. It's a dedicated lane. Trying to cut over after the booth would be pretty obvious.
It is also legal to drop guests off at the TTC.
For a number of years, we did not use the MK parking lot. In the last few years awe have. One advantage of the MK parking lot is getting to enter MK via the ferry or monorail. Both are fun. I don't think valet will save much time.
As for the poster who said they had to close a stroller, that's only the case, if you use the parking lot tram. We almost always find it easier and faster just to walk to the TTC. If you are arriving at MK near rope drop, then your parking spot will be an easy walk to the TTC. (even on fairly busy days).
I truly don't think you'll gain much advantage parking at CR. First, have to walk from CR to MK. We've stayed at CR many times. It is faster than the MK lot, but not a huge difference. Second, valet parking in the morning isn't instant; there's a line of cars at the security booth, and a line of folks checking in/out. Last summer, we did a split stay - GF to CR. I lost over half an hour dropping our bags at CR! and I left the bags at the curb. I didn't even wait for the CM to put them on a cart! I jogged from CR to MK- so about as fast as that distance could be done. (which was not easy given August heat). I was following the time because we had a FP. I missed my window by a solid 20minutes.
I'm not saying don't do it, I'm just saying it won't make a big difference- at least in terms of getting to the park. It might be a few minutes faster leaving MK, but it depends how long it takes to get your car from valet. If the difference was huge, more folks would do it. Parking in the MK lot is streamlined, valet is not.
I also don't see the point of arriving at the MK gate an hour before it opens.
However- it would be wise to leave your lodgings a FULL hour before the MK gate opens if you want to be in the park at anything approaching RD. You don't say where you're coming FROM, but the I-4 area sees plenty of rush hour back ups. A drive that takes half an hour during non-back up times- could take quite a bit longer if there is a back up.
On our last visit, it took us over half an hour to go 4 miles on I-4. It was painful. you may not have that problem, but you might. If you are not particular, I wouldn't stress it. If you have an ADR or your 3FP's, I would make sure to allow plenty of time for traffic.