Of course, the size of the inner tube must be right. This one fits, for example, if you don't have a super high rim: Continental 29" Wide 65/70-622 (Presta (SV), 29") The Cross King is really fun to ride tubeless, i.e. without an inner tube. This requires a special tubeless rim tape, a tubeless valve and around 1 dl of sealant. The tubeless conversion is even easier than fitting a tube.

Yes

Can also be a normal bike. It meets the standard for e-bikes that run up to 25 km/h, hence the E-25.