Beginner questions about clip-on wall paneling

[sawdustmaker]

To avoid having to figure things out too much when the time comes, I'm asking in advance.
When I'm installing horizontal wall paneling with clips, should I...

Install with the groove facing upwards or downwards?

How short can leftover pieces of paneling be reused for the next "layer"?

 

[Narren666]

Note upwards. Start from the bottom. Measure the wall so you don't risk ending up with a board that's too small at the top that needs to be ripped lengthwise.
The minimum possible piece is usually stated on the packaging.

Consider fastening the boards with a brad nailer or equivalent.
I did so. It turned out great.

 

[KnockOnWood]

When I'm going to install horizontal wall paneling with clips, should I...
Place the tongue facing up or down?

Alternatively, screw directly in the spring/spont, and then place the spring up and the tongue down.
Just as easy, because the clip must also be nailed or screwed.