SRP is an excellent polish for hand use because it fills scratches instead of removing them, not particularly effective against other polishes if using a rotary or DA machine though. For hand application, its one of the best around.
I used to swear by Megs Gold Class until I realised that its totally uneconomical and not as good as other brands. I use Wolf's WS-1N "White Satin" diluted to 1:500. Absolutely brilliant stuff:
I'd replace the water pump but I'm not at all convinced on the need to replace the tensioners as they're mechanical and not hydraulic. The original Honda tensioners will almost certainly be more robust after 150k miles than a brand new aftermarket item.