#1 Money grab. Likely not Honda recommended but probably BG product upsell. Gravy for the shop.
#2 Should get about 50,000 km before that is required.
#3 Most coolants these days are long-life and good for 5 years or 150,000km. The additives do wear out so you could consider this one.
#4 Most plugs these days are platinum or iridium and should go at least 100,000 km. No way car with that low of mileage needs plugs yet. Even copper plugs should get you 50,000 km.
'08.5 Mazda 3
'90 Laser RS-T
'07 Yamaha R6