You already have all the advise you could possibly need ;o) For me, I do rams head wedging and have never had an issue with it. I try the spiral now and again just because I want to be able to do it, so far my hands/brain haven't figured it out ;o) Simon Leach has a great video where he teaches the spiral wedging process, I need to go look at that again. He also teaches the wire cut and slap process. Look up his videos and search within his videos, wonderful stuff.
I only wedge standing up. I'm 5'3" and 115lbs, I need all the weight/height I can get behind my wedging ;o)
I never used to cone up simply because I couldn't. I never had an issue, probably because after I open up, I compress the bottom well before I even pull up. Now I do cone, but only a little bit. From what I understand, it's purpose is compression of the clay and help centering. I will say, I think it does help center. I don't do the tall coning like you see some people do, but it seems coning does help the centering. I now center like a pro! I've never had lumps in my clay, unless the clay just isn't mixed well. I don't think coning has anything to do with that. My pottery teacher, who has been doing this for nearly 40 years, throws her bags of clay on the floor many times before using. Maybe once per side or even more if she can tell it's stiff clay.