1) yes
2) no
3) if two is applicable, (see below), ignition princicple should be indifferent

There are some 4 stroke strimmer engines that follow 2-stroke principles and use a gas/oil mix to provide lubing (Ryobi?). AFAIK, the Honda GX series (gx25;gx35) are the only 4-stroke engines with a "wet sump" (it's more dry sump principle) that can be placed in any position without any lubrication problem due to their patented lube system.