Game Duration

It varies alot I find. I have some games I'm sure I started at the same time but one is a massive war now in the 60's, while the other has barely got anywhere yet is in the 100's. I'd say they've been going for maybe 4-5 months. It depends on how quickly the turns run. Some might have a turn every 2 days, while some might might manage a turn every day. A lot depends on the other players. If everyone is keen you'll get a turn every day, but the time it takes increases as your empire grows till the time between turns is extended so everyone has time.

When you're playing against another player the joint attitude will have an effect. I'm not one for making treaties with everyone I meet. Perhaps you'll meet lots of other players willing to just stay with a treaty and you can all slowly develop, or perhaps your neighbour isn't interested and preferrs to keep things interesting by atatcking as soon as possible.

What i have also found with all multiplayer games is that there is certain technique that work better than the rest.

In WOW for example there are cookie cutter builds that will always be stronger than the rest.

Are there any techniques in SE V MP that have the same result?
EG. Building loads of research - then following a certain research pattern. - Weapons,armor,sensors, etc
What are the avg RP points in a MP game by end game?
EG Building certain ships - High lvl frigates over low lvl dreds.

And using Emergency build in the 1st 10 turns...

All this knowledge, would come with some exp in multiplayer. But to be fore warned is to be fore armed.

It realy depends on the game your in, the people playing it and of course the mod (stock, BM, GidMod, Devnull,...).

You will need good sensors soon and for stock, applied research is most important. Also in every mod, getting all the colony techs as soon as possible is very important! Better weapons and point defence also help. Then it realy depends on what you are up against. If the galaxy is friendly (at least to you) getting way more research as everyone else is a very good idea. If not, you will not be able to do so, for your heavy fleet build up programm...

At the end you will mostly have lots of RPs... Depending on the galaxy size and mod, I typically end up with 700.000-1.000.000 in BM and 1.000.000 - 2.000.000 or more in Devnull and stock.

This: http://www.spaceempires5.com/en-US/node/2782 is quite a good guide to get started with BM multiplayer and usefull for other mods, too.
Said that, you realy should try MP on your one. After one-two games you will have way more experience, then anyone can give you through tips.
...But you will always find another thing to learn...