[Asterix]

With a light and a mirror, you can look up into the duct on the right side of the transmission tunnel to see the heater core. Look and see if it's crusty.

For the non-turbo engine, Pennzoil Ultra Platinum 5W30 is an excellent choice. Also, you can run a larger filter, like the Wix 51515. There's plenty of room for it.

It's more important to run the right coolant, since there's iron, aluminum, and brass in our cars. Toyota Red is a perfect choice.

 

[Asterix]

For that hose, and the #6 bypass hose (16283 in 3p's diagram), take your old one to your local parts store and poke through their hose collection to find one with the right bend you can cut out and use. That's the cheapest way to go.

The fun part for #6 is you have to remove the distributor/cps to get to it.