Check the suppliers forum and you should easily find a number of good websites with reliable material.
Storage is generally not a problem. Basically, minimize exposure to light, air & heat. Although, even if your spice completely oxidizes, it will still be rather potent (some prefer n-oxide to n-n). Some around here like to keep it in salt form rather than freebase. A few even prefer to keep it in a solution. (see q21's pioneering research into vinegar based DMT Acetate solutions and simple freebase conversions) It doesn't really matter.
Probably better to make a small batch. Start with 100gms of MHRB. That should net you plenty of spice for one or two people to mess with for quite some time. If you manage to get 1gm, this is like 40 doses. As you can see, your 2kgs of root bark will be a lifetime's supply.
You can try to enlighten your buddy, but don't be afraid to pursue your alchemy solo. Better not to teach extraction to someone who is mostly concerned with monetary gain, IMO.
A sitter won't be too hard to come by. Just find someone who won't judge you and who you trust implicitly. The physical effects can run a wide range, but nothing too hard to deal with. The reality is that you will be in no physical danger, and thus your sitter is not there to intervene unless you fall & bust your head open or some othe external situation. They are mostly moral support... and someone to prevent or deal with anyone who might barge in.
Do not shoot for breakthrough doses on your first times. Too many people make this mistake. There is no rush. YOu have waited this long to journey to Hyperspace... no need to jump the gun. Start with the smallest doses that have an effect, and acclimate yourself. You do not need to wet yourself to experience this stuff. As you are ready, and your vape technique is confident... you can progress deeper and attempt breakthroughs or whatnot.
Keep your mental, emotional and physical space clear. Comforting music playing or a safe natural setting...
You will be fine.