I made some changes to the assasin template to help expidite the transition to it from the now deleted character template.
To this end I changed the attributes in the assasin to match those in the old template. This means all one has to do to change is go into source mode and change "Character" to "Assasin" and all the attributes will link up except for the picture which now all one needs to do is type "File:" in front of the image name. No extra brackets or picture size is needed anymore.
Summary of changes:
All attributes are now Captialized "Name" instead of "name", "Born" not "born"
"Year's in division" was changed to "Years"
The "job" attribute was changed to "Profession" to match the old char template, it still is displayed as "Ocupation" in the actual page
Added First and Last Appeared as attributes
While this helps the transition it also breaks all the pages that uses the former version of Assasin. I've been going one by one to correct this however the Percy page is locked so I can't change that one.
By the way I'm going to change the template name to Assassin since that's the correct name
I'm back from my own summer Nikita hiatus. I did't realize some much activity had been taking place on the site. The page looks great!!!. I'm happy you and others have taking the time to update it. I also see you're an admin now; the last time I was on you were posting that you were still on Season 1 :-) I'm kind of bummed that the new achievement system is not retroactive but that's not a thing. Anyway I'm looking forward to this new season and helping this wiki page stay great.
Minor adjustments (color, text, spacing) on Template:P1, the template used within the CastPortal template
Color adjustments on the template used to display previous and next episodes
Almost forgot about your question; I use Photoshop for all my image editing needs. A very good free alternative is GIMP. As for the size, it mostly depends on the size of the image I'm using. I usually keep with width at 1920 pixels or less, and try to keep the height at 1000 pixels or less.