Answers to questions:

1- The rectus Femoris is part of the quad and is a hip flexor. It crosses both the hip joint and the knee joint so in your leg lifts this muscle is both flexing the hip and extending the knee.

2- Well, its not as cut and dry as you make it out to be. stabilizing the pelvis is important in climbing. But keeping one's feet on, on steep rock is a more a matter of inter-muscular coordination, combining stabilization of the pelvis with a number of other joint actions. Further, and to me most important, the orientation of the body to the line of gravity is constantly changing as a climber moves from side to side or faces the wall depending on the moves in question. This means that the Abs are not just involved in stabilizing via isometric contractions as they are in a leg lift; they are also aiding in lateral flexion of the trunk (as well as resisting lateral flexion to the opposite side) and undergoing lengthening contractions during trunk extension which feature prominently on steep moves. All this is to say I would rather see climbers doing training activities that target the various joint actions of the spine and hips (and knees and ankles) rather than choosing one that does not all that closely mimic climbing such as a leg lift.

3- I think the burden of proof is on your regarding this point. What muscles doing what stabilization do you see as being closely related in leg lifts and climbing? Also as Jay already pointed out if your feet cut loose on a steep route, then yes, the hip flexors are going to play an important role in getting the feet back up to the hold. But the more important question is what are we doing in actual moves on steep routes? Its in response to that question that I described the joint actions mentioned above. No offense, but from your posts I'm not sure you understand how the trunk and hips are used on steep moves well enough to make an accurate assessment.

re 3 and "burden of proof": I'm not trying to prove anything and I don't really give a damn if anybody "believes" me. I was trying to share something that I thought would be helpful. "content" if you will. That was apparently an error.

Well, I did pull-ups and push-ups yesterday and now my right shoulder is injured. Lesson learned. I had an indoor session planned today which I can't do anymore, it's really bugging me.

I'm going to order SCC and "9 out of 10 climbers" when I get paid next and just follow the advice in there.

I've looked into yoga, for flexibility, and found a few places close by that are fairly cheap. I might give them a try while my shoulder heals.

Injured from push-ups and pull-ups?

Are you sure it's not just Delayed-Onset Muscle Soreness?

Yes.

Yes, I'm sure.

Why does this entire thread feel like some underhanded plan to plug?.

this is a serious question: if leg lifts are only hip flexors and abs, why do my quads hurt the most when I do a lot of them?

Why does this entire thread feel like some underhanded plan to plug?.

If you want to do these activities because you find them rewarding that's fine, but you should not be doing them and expecting any impact on your climbing. Even something like finger hands which can be helpful probably won't in your case because you just don't have any movement experience.

At all levels of climbing the top priority is to get a high volume of high quality movement practice. This is all the more the case for the novice climber who knows none of the movement patterns involved in climbing. Your priorities should be:

1- Learn to make high quality contact with the rock or wall. this means quickly identifying hand and foot holds and the ability to establish good quality contact with the holds. The silent feet and glue hands activities are helpful here.
2- Learn the fundamental movement patterns found in climbing, turning, initiating movement from the lower body, how to move with straight arms (not a goal in itself but a good way to learn other skills)

3- Each day you climb either out doors or at the gym climb at a level at which you are comfortable. If the hardest climb you can do is 5.9 then you should be doing a high volume of 5.6 - 5.8 but if you find yourself struggling or just pulling yourself up the wall, just stop and get on something easier.

high volume of high quality practice should be every climbers mantra.

Anyway glad that you are psyched to climb but keep your focus on what will actually make you a climber. Good Luck.