Max Domi looks like he's done in Montreal. With Kotkaniemi's and Suzuki's performance in the playoffs, and the great defensive play from Danault, I don't see where Domi fits as a center, other then the 4th line. They always could keep him as a winger, but with how many teams are looking for a 2nd line center, it makes sense for Montreal to trade him. Minnesota have a great defense core, and Jonas Brodin had a career year, but since they're in need of a 2nd line center, acquiring Max Domi makes some sense. He had a 70 point year, is only 25 years old. I view Brodin as an expendable piece depending on how badly Minnesota want a center. You could add/remove picks from either side of the trade I made below, but the general idea is Domi for Brodin.
One thing Montreal has lacked for a while is goal scoring. Alex Killorn is my solution. The 30 year old winger could be expendable to Tampa since they need to sign Cirelli and Sergachev this offseason. He's signed at good cap hit for the next 3 years, and that's why I think Montreal should try to acquire him. He had 26 goals and 49 points last season in 68 games, a career best for him. He's been a consistent 15-20 goal scorer, and averages about 40 points a season. Tampa could move Killorn in a similar deal to the one which sent J.T. Miller to Vancouver last offseason. In return, I have Tampa recieving a 2020 2nd, 2021 3rd, and Joel Armia. Armia had a good year in Montreal, but lost his spot in the top 6 during the playoffs until Gallagher got injured. You could replace him with Artturi Lehkonen in the deal, but I believe Montreal would rather move Armia then Lehkonen. Either way, Montreal could retain 50% salary to make the deal more appealing to Tampa as they would get a 2nd/3rd line winger for under 1.5 mil for the season. You can edit the picks in return depending on how you value Killorn and Armia/Lehkonen.
If Montreal were to trade Domi for Brodin, they should look to replace the grit Domi brought to the team, and if Brodin jumps into the top 4, Kulak is probably expendable. He was great with Jeff Petry, but ideally he's a 5/6 dman. While Montreal could keep him as a 5/6, they have Mete, Romanov, Ouellet, Juulsen, Fleury, and more guys who all could play on the bottom pair, and with his cheap cap hit, he could be an interesting piece to a team looking for a 5/6 LHD. I believe the Rangers could work since Brendan Lemieux is an RFA this offseason, and Kulak could play top 4 with Trouba/DeAngelo if needed. Brendan Lemieux still has some offensive upside, but it's unlikely he becomes more then a bottom 6 winger. I think Lemieux would be a good fit on the 4th line in Montreal.
For the free agent signings, Aaron Dell was pretty good for San Jose last year, and could be the type of goalie Montreal needs, so they don't have to rely on Price most nights. Ilya Kovalchuk resurrected his career in Montreal, and if he can play anywhere near as well as he did last season, he will be a solid addition to the 2nd/3rd line. It's been rumored ever sincs he was traded to Washington that he would resign in Montreal in the offseason. Tomas Nosek and Dale Weise would be depth guys who could fill in if needed, and battle for a 4th line spot.
Swap Armia + 3rd vs Killorn is fair
But I don’t understand why you want another lefty, we need RH like Armia
I made this thinking about adding a goal scoring, not necessarily what hand they shoot. Maybe they move Tatar for a right-handed winger if it's that big of an issue for them