a) If you can lift it, go for the max. Having sais that, juicve on the water is one thing, when you then have to carry it 200 yds backto your ctruck, it;s becomes a very differnet proposal!
b) Definetly want an Etec? if you can live with the smell, you may find a twin cyl premix machine will give the same Hp with a lot less mass......
c) Maybe. there was a thread recvently about "biuggest you've ever pull started" - some havve yanked 150Hp to life (emergency start having removed the cowl) . Years ago I was on a rescue boat with a twin cyl Mariner 40 Autolube. Easy to pull start, as I did lots of times that week. Granted I was younger back then.....
Where I'm going here is that a lot of 30s are actually de- rated 40s, so the differnece to pull start will be negligible.
d)
usually heavier, although Hondas & the new generation of Yams appear to be comparable with auto mixing 2- strokes. One thing to watch - if you aren't towing it, they are very fussy as to which way down you lay them so the oil in the sump stays in the sump...
Thoughts for the mix -
Suz DT30 (elect start version) - approx 75Kg.
Merc Clamshell 50/ 60 Hp - (again elect start version) 82KG.
As the merc was sold pre "prop HP rating", it's probably closer to 45Hp at the prop....
Nothing is ever simple!