RohanMenon
Planets in their own rulerships (proper places) are stronger than those which are not.
Aha! I'd been interpreting 'proper place' as not-2nd-6th-8th-12th. Hence the confusion as to where to start counting from. I assume rulership == any kind of rulership, (domicile, triplicity, exaltation. Term? Decan?) rather than just domicile. Very useful. Thank You.
as is
Alien places are the Detriment of the planet in later periods. So the Sun in Aquarius is in an alien place.
For your individual queries at the end:
[1] is the pre-natal lunation (either Full or New Moon) it can be used in the length of life calculation
[2] Basis is the foundation on which the nativity is based. It gives some indication of eminence, especially as it is related to both Spirit and Fortune. The Lot in a good place and its ruler in a good place are indicators of a strong nativity. As you might by now realise, Basis is always below the horizon in he lower hemisphere. Placed in the fourth of fifth is very good. Placed in the sixth is weak, especially if it is also averse to the Lots from which it is derived.
[3] It simply means their in one of their own rulerships.
[4] Ditto
Thank You.
Random Thought: It might be an educational exercise to take the short list of principles you elucidate above and break down individual rules from Valens to see how they are constructed/how they work.