The Youtuber Artifexian https://www.youtube.com/playlist?list=PLduA6tsl3gygXJbq_iQ_5h2yri4WL6zsS has some good information on the topic, in which he explores star system and planetry building using equattions. (which i am currently compiling into spreadsheets for ease of use)
The mass you gave is great (3.5 Earth Masses is the absolute maximum size i'd use to make a habitable world), and your moon should be less than the mass of your planet, but greater than 0.25 earth masses. This may turn your planet and moon into a binary planet system (like Pluto and Charon) so when calculating things such as orbit you may need to find the Baricentre of the two bodies first.