POWER MOSFET - Thermal Design
1) since you're only dissipating about 0.2 W I would say this is more than OK assuming that this PCB isn't in a very hot environment. It is possible to calculate the thermal resistance (to ambient) using tools such as those on TI's website.

2) Possible: yes but I would not choose to do that! What you are then doing is temporarily giving the MOSFET a higher resistance and that will temporarily increase the power dissipation in that transistor.

The inrush current also increase the power dissipation temporarily but the total energy that the MOSFET needs to dissipate will very likely be much less. 

Do note that as long as the MOSFET can handle the peak current and the peak power. dissipation there is no direct issue unless it gets too hot. The MOSFET's package and the PCB cooling area will require some energy to heat up (thermal capacitance) so temporarily it is OK to have a higher power dissipation. As long as it does not last too long.

I would choose to switch the MOSFET on as fast as possible and not try and limit the inrush current. It could be better to use a PTC to limit the inrush current.

This can all be calculated but it's not that easy. Usually a thermal model needs to be made. This can be done in a circuit simulator where the voltage then represents the temperature.