Hi Sagets, I recommend you to open the LCIA methods in openLCA and check out the descriptions in the "General information" tab as well as to simply check the characterisation factors in the impact categories tab.
1) The version openLCA offers is 1.0.9; You should be able to cross check the CFs on the web pages provided in the description: " [...] more information about the method can be found at : http://eplca.jrc.ec.europa.eu/uploads/LCIA-characterization-factors-of-the-ILCD.pdfcontact
Version 1.0.9, May 2016. Method checked against SimaPro 8.5."
2) As far as I know there is not a time frame for this but in general we always strive to have all important methods readily available for openLCA. However, constraints in time and resources sometimes limit us in what we can provide.
3) In principle, openLCA can run any LCIA method ... you just have to create it ;-) A partial difference between CML IA and CML 2000 is that the latter features an impact category "Abiotic depletion (fossil fuels) - CML-IA baseline". You may also want to compare some of the characterisation factors and check if there are differences (via the impact factors tab). I do not know this from the top of my head right now.
4) If those methods have impact categories which you need to cover all the impact categories which you want to address,- yes, you can run those three LCIA methods and stitch the results together. However, you can also create your own LCIA method. As mentioned above, we sometimes struggle to integrate and keep all LCIA methods up to date (still, we currently have more than 70 readily available) and we always appreciate support from users who are keen to create new LCIA methods for openLCA and who are willing to share these methods with other users and the openLCA community.
I hope this helps.