Speed is the only interger value, (non-percentage) for primary.
Base Stats for accuracy, crit chance, crit damage, crit avoidance, potency, and tenacity are all in percentage so the mods are also in percentages.
Your Teir info. Is a little off.
T1-T5 can all have 4 secondary stats. Almost every mod at grade a (level 12) will have 4 secondary stats. Every once and a while one of the added stats actually matches a stat already present so that stat just goes up and level 12 or higher mod may show less than 4 secondary stats. Ex 2 secondary stats of +3 speed and +2 speed will end with a secondary stat of +5 speed.
Mod grades.
All mods reach grade A/gold at level 12. This is the point when ago secondary stats are shown and have reached final value. Leveling from 12-15 only improves primary Stat.
Stating Mod grade/color only means more or less secondary is know before leveling. As you level some of the shown secondaries will upgrade or you will get new ones. Max of 4 secondaries. I have seen starting grade E end with higher secondaries than starting grade A.