Front-load against top-load is covered in our washer guide. The installation questions are the ones that decide whether the machine can go where you want it: hookups, the floor under it, and whether you intend to stack.
A washer needs hot and cold supplies, a drain, and power. The drain standpipe has a minimum and maximum height specified by the manufacturer: too low and the machine siphons while filling, too high and the pump struggles. It is a specific number in the manual rather than a matter of judgement.
Front-load washers spin fast enough to shake a room, and on a suspended timber floor, particularly upstairs, that becomes noise and movement through the whole house. A solid, level floor is worth more than any vibration-reduction feature. Levelling the machine properly on its feet is the single most effective fix.
If you plan to stack a dryer above, the two units generally need to be the same brand and a compatible pair, joined with a manufacturer stacking kit. Stacking without the kit is unsafe. Top-load washers cannot be stacked at all, which is often the deciding factor in a closet installation.
A front-load door opens wide and usually only one way, though the hinge is reversible on some models. In a narrow laundry closet that swing decides which side the washer goes. Pedestals raise the machine to a more comfortable height and add storage, at the cost of overall height under a shelf.
More depth: front-load against top-load and which brands hold up.
No. Stacking requires a front-load washer, a compatible dryer (normally the same brand and matched pair) and the manufacturer's stacking kit that locks the two together. Top-load washers cannot be stacked. Stacking without the proper kit is genuinely unsafe given the forces a spin cycle produces.
Usually because it is not level, or because the floor flexes. Adjusting the feet so the machine sits solid on all four is the first and most effective fix, and shipping bolts left in place after delivery are another common cause. On a suspended upstairs floor some transmitted vibration is inherent to a fast spin.
A standard washer runs on a normal outlet, though the manufacturer will usually specify a dedicated circuit. Combination washer-dryers and some large-capacity machines can require more. Check the electrical specification in the manual, especially in an older laundry room where the circuit may already be shared.