Call the phone number on 罰單 for the options

There should be a phone number on your citation(罰單).

1． 我看到罰單上有寫“points will be assessed as applicable” 這是不是先生的駕照的point呢？就是說交了錢還要扣點？
Most likely.

2如果是，這會不會影響我們以後車保險漲價？他當時開的是租來的車付帶保險。
Probably. Since it's the only moving violation your hubby has, the impact on your auto insurance is probably very minor if all.

3是不是可以選擇上課來免扣點。如果是，還要交罰單嗎？
It's possible to take defensive/safty driving class so no point will be taken and the violation is not going to your hubby's record, meaning your auto insurance company won't even know such citation exists. But you have to call the phone number to know if you have such option. Changes are you can do that. The fine is not necessarily reduced as it's revenue to the city/county where the police pulled your hubby over.