The typical amateur radio / SWL budget will rarely allow for sufficient protection from a direct lightning strike. More often than not, the measures taken help minimize damage from a direct strike but more importantly they mitigate damage from near lightning strikes and static build-up.
If the goal is to bleed static and minimize damage then mast should be grounded (this is also an NEC requirement). The grounding should be carried out with a heavy gauge conductor (minimum of #6 by NEC) leading to a ground rod. The efficacy of the ground can be improved by using wide copper straps. The ground rods should be tied to the house system ground rod(s) with a minimum of #6 AWG wire.
The cellular industry has promoted bringing the coax down to the ground level and installing a lightning arrestor bonded directly to the ground system at this point. This is considered a best practice for amateur radio installations as well. If you cannot route the coax in this manner, installing a lightning arrestor in the coax at the mast and bonding it to the mast ground may provide some level of protection.
Be aware that your mast mounted pre-amp is considered lightning fodder. There is little that can be done to protect it from a near lightning strike when it is located so far from an effective ground. Some people advocate the use of an RFC (radio frequency choke) inductor across the input. This will offer some degree of protection but due to the rapid current rise (di/dt) during near lightning events, it is not likely to stop all damage.
Your resistor across the dipole legs will prove helpful to bleed of static that is generated by winds and nearby storms. You should periodically inspect this resistor as it too will be sacrificial in the event of a nearby strike.