On lube Moni, it's YMMV. I started with KY which while not my first choice was available at CVS and is cheap.
I bought one 4oz tube to fly with and had my gf pickup 2 more when she arrived and I only just finished those 3 tubes. That's for 3 dilations per day using sizes 1 and 2 nearly every time (my very first dilation, of course was at Wittenberg's office and they used surgilube).
For position the first time they had me in a gyno exam chair my feet were in the normal stirrups, thighs flexed about 45 degrees wrt torso. For the first few times I emulated that in bed, using a pillow to rest my feet at the desired angle.
Because some of the skin at the full depth of the PI inversion wasn't adhered to the vaginal walls, she had me dilate the first week for 30 minutes at a time instead of their usual choice of 10'. I found it hard to keep legs kicked up for that long, I took to a close to flat/supine position with my hips turned slightly and legs slightly akimbo. While I had my gf there, I had her help put a pillow under my knees. I found and still find completely flat / supine uncomfortable, due to the fairly strong bend in the dilator tip. Of course YMMV, use the position that you find works best. If I had a private room at work I know I'd outfit it with a cot but the right reclining chair could work also.
About amount of lube, whatever lube I use (now switched to surgilube) I don't use a lot. I based my guess of how much on lots of experience with sexual penetration vaginal & anal and with penis, toys and hand/fisting. Of course I'm familiar with the idea that "too much lube is not quite enough".
So my approach with this has been "the right amount, not too much" my reason was that I didn't want to be cleaning excess lube or introducing more of the stuff than was necessary because I didn't imagine it would be helping with healing, nor would excessive rinsing to remove excess lube. Ok so call me a minimalist, and I'm also quite cheap, dinna faish spending more pennies on KY than necessary.
So what was enough for me was to lay down a line of lube maybe 3/4" long at the diameter that it came out of the tube at most and use a finger to spread that evenly over the full length of the dilator, somewhat less on the second one as I knew the channel was already lubed. My experience was that lube was really only needed for getting past the labia and the vaginal canal itself was plenty well lubricated by discharge/exudate. That's what I did for my very first dilation, supervised by the doc herself.
For the first couple of weeks I used a nitrile glove on the hand spreading the lube (happily I get those free from work). Once I got back home, thw vaginal canal was clearly mostly healed and I switched to simply washing my hands first.
