The difficulty adjustment is an average across the two weeks.  Some blocks will take longer than others.  My estimator is currently predicting 45898197.93 although I'm imagining this will probably decrease some.  Unless a bunch of people are getting their miners in, which is possible and then fuck.

Stupid question....Where's Slush? He's like the only pool OP who doesn't post at his thread....

how long are rounds on slush? and when do they start/end?

is it best to use slush pool for 24/7 mining?

how long is each round though? or is it random

You may want to find a Wiki on Bitcoin somewhere and just read up a little.  All rounds for all miners everywhere are (essentially) random.

i had noticed that..trying to get my head around all the different pools etc. aswell as reading wikis it helps to ask

one more question, how long does it take for the btc reward to be confirmed? latest one says validity 91 confirmations left?!?!? google it but could not find the answer   sorry if im being an idiot

100 confirmations with Slush's Pool.

So what you are saying is anybody in the world who starts working off the block that we found here, by adding new transactions to it? Phew get it out there!

Others are not adding transactions to our block, they are working on new blocks based on ours.
Miners always work on the longest chain of blocks.
When we found a block, Slush waits for 100 new blocks being found based on ours, to make sure the block really is contained in the longest chain, and not on some orphaned fork.
Sometimes two blcoks are found quite fast after each other (by different miners) and are not based on each other.
In that case, one will get invalid when the other one wins out on having new blocks being based on it.

Actually, blocks could be considered mature quite a time befor 100 or 120 confirmations quite safe, cause even a fork with some blocks in each chain is very unlikely, let alone tenth of blocks.
But in case a part of the network is seperated from the rest, waiting longer adds a little more safety.



tl;dr
Slush makes very very sure the block is in the longest chain and thus valid before paying you for your work on it.