TLDR: This is your gaming world and you know your players and their gaming styles, expectations, amount of detail they like in their games. You start with your rules and tweak them as you go so everyone has a blast and it's fair to everyone. Every group is different, as long as everyone knows the rules and they are the same for everyone, you're good to go.
Agreed, 50 Dev Points per level is a LOT of points, especially if you aren't allowing many secondary skills. We allow all of the skills in RM, just because they are there does not mean the player has to purchase them. To this day, no one has EVER taken MidWifery. One player has taken Animal Husbandry though. If you're not allowing a lot of secondary skills, there's no need for the 25% DP for secondary skills, there simply aren't many to choose from anyway.
We've had players with as few as 24 DP per level and never had a problem with skill purchases. The player just focused on more important skills and didn't buy very many "colorful skills." In 30+ years of playing, DP vs. # of available skills has never been an issue. The players simply did not buy the skills they didn't want. As a GM, if a player buys an 'odd skill' like Architecture, I try to find a way to work that into a game so the player doesn't feel like he's wasted DP. Ironically, the Architecture skill has come in handy several times and has helped the party break into places, break out of places, and locate secret areas. The player was very creative and rolled really well. LOL
The easiest method for skills that we use is the Master Skills Table in RMC-II. It is the bible of the game. The most essential book for PC creation. That skill list is more than enough for players, especially if they are starting out. There are optional skills in later Companions that are really nice. Holding Breath, Omen Lore, Weapon Casting, etc. They are offered, but no one has to buy them.
We have an interesting game world. We allow all of the non-magical professions from all of the Companions, however only Elemental Companion and Alchemy Companion allowed for spell users. Long story short: It is the Renaissance Period of our gaming world Alchemy is the new 'science' as is Elementalism. Magic, as it is known, has all been explained away by what passes for science. Magic potion to heal burns? Just Aloe. Player frozen in place? Slime from a very small, very brightly colored tree frog. Player being under mind control??? Hypnosis! Science has explained away magic and religious miracles. (So they think) People are enlightened now!
Sense Ambush Assassin is an essential skill and is very different from General Perception. It also works as the direct counter skill for Stalk/Hide. Stalk/Hide we split up into two skill values. The Stalking part is (SD/AG) and the Hiding part is (SD). Sitting still while not being noticed and moving while not being noticed are two very different mechanics. General Perception is (IN/IN/RE) and Sense Ambush is (IN/RE), the stats could yield different bonuses for players.
We don't require the "training in a skill" before leveling up. It never made sense to us. If a PC is fighting with a sword and using it, he will eventually improve. He doesn't need to go to a weapon master to level up. A spell caster should be studying his tome of spells and learning the next level spells. As he practices casting spells, he becomes more in tune with the magicka and the nuances, and is able to cast more easily, we don't make the mage go back to the academy to learn from a master.
For maxing out levels, we do allow the lowering of stats on a stat gain roll because it happens so rarely and leveling up from level 1-5 is fairly quick. We do automatically reach the potential value at level 5 regardless of the temporary stat and we do away with stat gain rolls at that point.