gday dr-307
the timber framing code makes provision for the posts to rest on a sole-plate, as opposed to being tied into a footing below the surface. depending on the height above ground, wind forces, construction, this may be a suitable and economical solution to your needs. the paving is there and it falls therefore substructure drainage is not an issue. if the whole area is paved & the overall height above ground is less than 1m then this may well be an option.
with the substructure you need to decide if you want to span further distances with less but more substantial footings, or vice-versa. something to remember - every stirrup you put in will cost you around $20 once you factor in time and materials - maybe a little more because you need to get through a bed of concrete 100 thick that presumably has been sitting there for some time - personally i would be trying to tie into this to take advantage of it. having said that, you need to verify that it is indeed 100thk and suitably strong - it may have been a wet mix because it was only ever intended as a layer under the pavers; but then, maybe the pavers were laid over the top of an existing slab to change the appearance? 100 thk does seem a little excessive for a paving bed...
speculation aside - to answer such a question, you must name names...
what are the dimensions? where is it being built? what type of timber are you using? at what spans? will there be a roof and will it be integral to the substructure or mounted afterwards? what about handrails? how (if at all) will you attach to the existing residence? what parts of the deck do you want to achieve yourself as opposed to how much will you sub out? can you weld? and finally, what is your budget?
here is some food for thought... all these posts have used discussed differing methods for bearing the load...
tall deck next to a pool
http://www.woodworkforums.com/showthread.php?t=58407
low-clearance, stirrups
http://www.woodworkforums.com/showthread.php?t=55825
http://www.woodworkforums.com/showthread.php?t=57608
low-clearance, many stirrups
http://www.woodworkforums.com/showthread.php?t=58502
footings into sandstone
http://www.woodworkforums.com/showthread.php?t=55187
telegraph poles
http://www.woodworkforums.com/showthread.php?t=47807
stumps on/in to concrete
http://www.woodworkforums.com/showthread.php?t=56136
stumps direct-buried
http://www.woodworkforums.com/showthread.php?t=58109
r's brynk