In your picture , you would "try" to take it apart from right to left ,(note the lock nut to the right , it holds the Compression adjuster/fork cap , and take note of the exact amount of total clicks , even if it ends in a position halfway between clicks , when reassembling , you have to adjust the needle assembly and count the clicks to get it back to where it was , so try not to move the locknut far from original position as you will end up with one fork with less or more clicks than the other , try to measure where everything is and return it as close as possible to the position it started , as that will make it easier when reinstalling as it keeps any chance at damaging the new seal to a minimum
IF you can remove the Base Valve with the "tool" by holding the fork cap with a 32mm wrench or socket or fork cap tool before loosening the lock nut , then remove it and replace the seal from that side , so you won't have to worry about the adjustment
And yes the "tool" i pictured holds where you put the arrow in your second picture , your 3rd picture is in fact where the seal rests , note the orientation of the seal when removing and be sure to install it in the same direction , and you should seek Suspension shops or suppliers , such as Race Tech or Factory Connection , etc. , to get the proper seal , you just need to tell them the year/model/make/ (country where the bike was sold if not in the U.S. as some euro parts differ from U.S. models) you did not mention where your from but i am assuming New Zealand by guessing at your user name , and yes the free play of the spring is "normal" , no issue with that
To remove the seal you must remove the 2 outer bushings , a C-Clip and washer , underneath the washer is the seal , then after everything including the O-Ring is removed , clean the excess oil off the piston , then heat it with a Propane torch at the seal , till the seal starts smoking , then use a screwdriver to pry it out , it will easily come out once its heated , you can hold the piston in a vice if you just gently close the jaws on it or use vice grips to hold it while heating , clean the piston off with cleaner once its cooled , and/or a Scotch Brite pad , then install the seal in the direction it originally faced (without heat , usually a deep socket works well , make sure it goes to the outside edge of the seal not down into the recess , then reinstall the washer and C-Clip and O-Ring and Bushings , and reinstall onto the assembly , and check all your clicker settings , and adjust if necessary , install in cartridge , bleed , and reassemble the fork and your done... Just count clickers and measure stuff before disassembly and write it all down and you should be fine
EDIT:
Forgot to mention , to use Teflon Tape over the threads of the shaft where the piston goes , otherwise you will damage the seal as the threads are very sharp .... hopefully you read this before you assemble.....
EDIT EDIT: 2/8/2018 - 10:35am
Forgot to mention
when reinstalling the needle assembly , have the needle clicked all the way out (CCW) then click it in 24 clicks , then screw it on till it just touches/bottoms the needle , then tighten the locknut to it , that way you don't have to worry about measuring , check the other side/fork and make sure it has 24 clicks as well , if not adjust the just installed one so it gets the same amount of clicks when it bottoms as the other fork , so they match........
AGAIN .... IF you can remove the Base Valve with the "tool" by holding the fork cap with a 32mm wrench or socket or fork cap tool before loosening the lock nut , then remove it and replace the seal from that side , so you won't have to worry about the adjustment , sometimes the base valve sticks on , and that is why i suggested doing it from the needle side....... hopefully you read this before you start ...my bad , been preoccupied with my suspension and getting my bike back together for the weekend and just forgot to mention a few key things that i should have mentioned in the first part of this post .....