I haven't found it either. p28 for RM2 ChL&CL is the herbs and poison charts, and i does not provide that kind of details. RMSS/RPFRP does not provide the info in the standard rules. I could not find it either in the RMU poison and disease section (at least in the publicly available Beta book).
It does appear to be above the charts on ICE1300 RM2 Character & Campaign Law p28, within the Form and Preparation section. You do need to look carefully. I missed it the first time, too...
"Paste - Raw matter is made into a paste that may be put in food or drink or be applied to tools or weapons and stays effective for one week, or until an object or person is struck. If poison is used and a crit obtained, foe must make an RR or receive the effect. If the effect is merely hits (no crit), the poison is gone."
I'm an RMSS/RMFRP player, and have always played that a crit must be obtained for the poison to take effect. However, I've never found much info about it in the rules.
1) how many arrows/short blades/long blades does was dose allow to be poisoned?
One dose, one application. Applying it to one arrowhead may take the same amount of poison as a sword - you don't necessarily need to coat the entire surface of the blade, after all.
2) do you require PCs to make Poison Lore and or Use/Remove Poison skill checks to prep and/or administer it
Use/remove poison, yes, unless they're doing it magically (Magent lists etc). Poison lore may give a bonus to use/remove poison, but isn't a requirement.
3) in combat, how do you rule any amount of damage done by the poisoned weapon administers the poison to the target or is a critical is needed for it to work?
Crit is required. However, I do use the RMFRP effect descriptions on p93 of RMFRP GM Law, which means a successfully applied poison may take quite a while to actually start taking serious effect. Interestingly, I don't see this in RM2. It does make poisons in combat in RMFRP much less useful, since by the time a poison starts kicking in, the combat's usually over. Poisons taking this long are more useful in sneaky situations than melee.
4) how long does the poison remain potent for once it is put onto a blade?
Until you hit something with the blade, or about a day.