There are so many playstyles in Eve that could benefit from an expanded contract system. Just a few that come to mind:
-Salvaging
-Signature scanning
-Hired gun
-Support vessel
-Mining and mining command
-Bounty Hunting
-Recon/intell
-Search and rescue
So many opportunities with an otherwise simple contract system. The more ways you cater to specific playstyles in Eve the better!
How would you account for and verify that the requirements for these contracts would be met?
A lot of these could use a time specific pay rate and or conditions, with the contract creator having a grace period to terminate the contract if they deem the contractee is unable to carry it out. Some filtering methods could be used, minimum remote repair/dps/mining yield etc. when creating contracts.
Just off the top of my head…if there is a will there is a way.
Some of those might work (mostly the numbers based ones) but I’d say that contract types where failure or completion is open to interpretation and not completely fixed are very easily gamed.
Search and rescue for one: lets say that I offer you a contract to try and get me out of a WH within a certain time frame. As you put in all the work and effort to find the WH connections and guide me back to the high sec hole I simply won’t jump through and wait till the contract times out. I just bookmark it and wait, now you get nothing and you lose your collateral.
Conversely, what if I get destroyed by others, what happens to your collateral? What if I wait for you to accept the contract and then have an alt destroy me so I get your collateral?
These are all considerations that aren’t going to work with “simple contract system” 
I would like to add ISK lending (secured with Assets or without) , it would allow economic growth to accelarate dramatically.
I’ve got an investment you might be interested in that will double your isk.
on topic
You’re talking PC missions, not contracts. Have you tried searching for corps that do all of this, because I’m sure they exist for a great many of these tasks.
bumped this into Player Features & Ideas - EVE Online Forums
No, I’m talking contracts. I’m talking about going to the global contracts board and fulfilling player made “missions” for those of us that like being a single mercenary or private service.
These can be sorta done by gentlemen’s agreement. A long time ago there use to be this feature known as freeform (see CCP news: EVE Online…) it was taken out several years ago - probably from abuse by the players or due to the complications, I do not remember.
PC = Player Character
NPC = Non-Player Character
PC Missions = Player Character Missions = player made “missions”
You disagreed with me only to repeat what I said. Good one. 
I see, you don’t want to play with others in a multiplayer game, so you want CCP to make things easy for you in a game designed to be played with others.
This is only a rumor, but I heard somewhere that CCP is working on a corp/alliance mission framework for future release. I cannot remember where I heard that, so I cannot verify it at this time. What you want may be coming at some point down the line.
This seems like the existing Projects that corps can do. Not all the features are currently included, but we can request that addition.