Strength wise, Epi and ArA are solid. I have used both and enjoy them almost equally. X-Gels or MassMax XT would be a good option there. Users have reported that MassMax XT has provided them with an increase in scale weight, but they also report they look leaner when they look in the mirror. MassMax XT would help with both your strength and lean goal. But also keep in mind that leaness is also going to come down to not eating at a significant surplus.
I have also stacked AlphaMax XT and X-Gels at a very small surplus. I saw an increase in strength, smaller than MassMax XT alone, but I looked leaner with this stack.
Depending on your MAIN goal, I would say to pick one over the other (focusing on lean gains or strength) I would go with different options. For pure strength, I think a MassMax XT and X-Gels stack would be great. If you want to see more of an increase in lean body mass, but only with a small jump in strength, I would stack AlphaMax XT and X-Gels. AlphaMax XT and MassMax XT could also replace the first option. Whatever you decide to go with for your strength supplement, AlphaMax XT would be a great addition to promote lean gains due to the forskolin.
Forskolin increases metabolism, burns fat, breaks down triglycerides, and increases lean-body mass
The thyroid stimulating strength of forskolin has been compared to TSH (thyrotropin). Thyroid hormone levels are important for leanness.
Forskolin has increased total testosterone by 16% in male subjects during a 12-week trial.
https://www.t-nation.com/supplements/burn-fat-pile-on-muscle-with-forskolin
Fat Mass: The colforsin group lost 4.52 kilograms (9,94 pounds) of fat, plus or minus 5.74 kilograms, while the placebo group lost only 0.51 kilograms (1.12 pounds), plus or minus 1.91 kilograms.
Lean Body Mass: The colforsin group gained 3.71 kilograms of lean body mass (8.162 pounds), plus or minus 4.07 kilograms, while the placebo group gained 1.57 kilograms (3.45 pounds), plus or minus 2.56 kilograms.
Testosterone: The Testosterone of the colforsin group rose 33.7 percent, while it decreased 18.35 percent in the placebo group.
https://www.t-nation.com/supplements/dont-kill-the-messenger
The total body weight of a mixed group of men and women in a 12-week study decreased from 74.7 kilograms to 73.5 kilograms while experiencing increases in lean body mass (without weight training).
https://www.t-nation.com/supplements/tip-the-t-boosting-capsule-you-need-to-take
https://www.ncbi.nlm.nih.gov/pubmed/16129715
https://legionathletics.com/forskolin/
http://www.infinitelabs.com/forskolin-reviews/
However, if you have never ran MassMax XT, AlphaMax XT, or X-Gels before, I would run them solo first, or for at least four weeks before adding anything. That way you can see what affects you and how.
For mobility, the best thing will be to find a good mobility program and performing it daily and then a few times per week. In addition, I would do post workout static stretching and pre workout dynamic stretching.. The muscle group(s) you're hitting hat day will dictate what type of dynamic stretches you do pre workout. I would also foam roll post workout, that will help with mobility as well. If you are fairly inmobile, you may have to do more at first, but once you start becoming more mobile, you can cut back. There are some things I would do daily, but the time you would need to hold each stretch or perform would decrease.
As far as mobility drills go, I like Defranco's Agile 8
https://www.youtube.com/watch?v=3B-3Khbht5s
Limber 11 is also solid
https://www.defrancostraining.com/joe-ds-qlimber-11q-flexibility-routine/