A. - Yes. The Artist grade has been used successfully on older concrete for many years. Many projects have concrete as much as over 100 years old and stained fine. I have walks and patios at my home that is 37 years old and was rough, worn and ugly and we stained them this summer and they turned out great. However due to the age and roughness I would figure on the concrete drinking up more stain so you'll likely only get about 150 to 200 sq.ft. per gallon.
It's always better to try acid stain first. If it doesn't work out then you can paint it with acrylics with no problem but if you use acrylics first and end up with the mess that you most likely will, it's alot of work and expense to get it cleaned up and ready for acid stain.
Earl Choate Ph.D.