Ungod

To start a research document, or collection (a Knowledge doc), you'll have to spend a wishpoint. The said K doc will be joined by the people you invite and is used to pool knowledge on a particular topic.

The greatest achievements in MD are having a good time and enjoying the results of your continuous work in having a good time (this point of view is hedonistic, of course, you assume that happiness is the end goal in life).
For those who are of a different opinion on what it means to achieve something, the game offers some visible means of progression for your character in the realm - such as a number of activity days (achieved!), a number of spelldocs acquired(!), of creatures upgraded to max and so on. These feats of your character are called 'achievements' and must be unlocked first in order for you to see them displayed nicely on your page; that is done in particular scenes. Activating them is a requirement for displaying them, but unlocking in itself does not mean completion. Therefore, activate them as fast as you can and achieve them at your leisure.
These achievements are standard, but some are of more interest since they reward Wishpoints. So get out there and achieve them all!

Nobody dies, it's all a ruse... Well, nobody truly dies because we've been under a resurrection spell since about 2-3 millennia ago. This is why they still move about as corpses. They also speak as if nothing happened, no personality disorder occurs.
As to how death happens in MagicDuel, it may involve a bad choice in a quest, but typically it involves a bad choice in your interpersonal relationships. A careless remark, a misplaced emoted smirk, is all it takes to tick some people off. Add to that the existence of 'kill items' in the realm, as well as assassins who kill for money (usually), and death happens.
Kill items require gold to operate and you can also order a hit by paying enough gold. 

A fair number of creatures need you to be at least MP5 to be able to upgrade them to their last level. One way to deal with the problem of seeing the mindpower advance requirement on the creature page is to simply climb the stairs to adulthood and reach a higher mindpower. Another is to use a wishpoint and upgrade a creature beyond its normal level for your current mindpower.
Ah, there's also the possibility of simply saying there is no problem, since you do not need to evolve your creature any higher and it was an error to think the grasan cannot live in peace as it is.

You are in luck, because there is. A certain item can be bought in the MD shop and it's called token removal gel. It may be a sticky business, but the gel will remove the token from that creature and turn it into an inventory item, just as advertised. Now that is an honest business!

Unless you like the condition of metic, becoming a respectable citizen of a (more or less respectable) land is something to be desired. For starters, the beer will be free* and you will not have to mingle with the riff-raff of No Man's land (people with no loyalty to nobody) anymore. You will miss the times you argued about the number of pillars GoE has, but hey, there's plenty more pillars to be miscounted elsewhere as well.
The (sum of) benefits of joining a land are as diverse as are lands. This might be under the spoiler category, so I cannot detail too much, but from stat increase to regen timer decrease, there a number of things that alter your perception when joining a land. However, you will find heat gathering way easier inside your land and heat loss much more penalizing when outside your land.
Other benefits include the possibility of acquisition of shared tools, which usually require you to satisfy one or both conditions: loyalty points and citizenship. This comes in hand with fighting resource wars over who depleted what, when and why. 
Making your way up into the world also involves NOT bypassing citizenship, as to join an alliance and become a respectable whatever means being a citizen first and foremost; you also get to have a say in land votes and king decapitations. You can also become a KING and get that shiny medal which does not disappear after your kinghood does. 
Well, the benefits are too many to list here, but I think drawbacks exist as well, and some may prove equal to the benefits. For instance, you might not choose the best land there is and regret it bitterly afterwards (unfortunately, because it would count as publicity, I cannot disclose the name, you'll have to figure it out by yourself *wink wink*). Ponder the question, but remember there is no obligation to be a (respectable desirable decent intelligent full of potential) citizen. None at all!
*promotion restricted to a few first items

Just like your brain cannot focus for too long on what's in sight, or learn without breaks, so you cannot explore the new and exciting without a break. Even great explorers like yourself, thirsty of knowledge and wanting to pioneer, cannot do so without getting tired.
Whether you travel new lands or acquire new creatures, at some point you might run out of exploration points, at which point you are forced to stop and let them replenish naturally. Have a coffee, relax - the Explorer's League provided you with a hammock, right?