I'm a bit mixed about Suarez coming to Barca. He's an amazing player and would bring much needed quality that would make our attack more devastating than what it already is, but to work well in tandem with Messi he's going to have to play in the correct role otherwise it just won't fit.
To get the most out of the Suarez-Messi duo, Suarez will have to play on that left/central channel. When Messi is starting a move he almost always faces on his left side driving from the right. Most of his runs and throughballs come from that position and he rarely services whoever is on the right side. Best example of this is his hattrick of assists for Tello against Levante:
Suarez himself is stronger on his right foot as well even if he can shoot with both. He'd get the most amount of goals for himself on the left as well as combine with Messi enough to assist him from that position. Both of those players running at defenders in attacking moves would cause regular goal-fests plus Suarez will occupy CB's for Messi to have space and occasionally give us a heading outlet from crosses. Even if Suarez will be much more of a #9 than a LW, he'd still likely have to be on the left side of Messi for the duo to work.
There are a number of ways to approach this. The best for me is Messi in a free role stemming from the right side like he did vs Milan while Neymar is on the left and Suarez in the center but to the left side of Messi. If Alexis is included in the Suarez deal then we can even have Cuadrado owning the right flank entirely like Alves did in that match.
Any system like that is much more star studded on paper than it is operational in real game scenarios. For one it decreases our defensive stability as Neymar/Messi don't defend and Suarez doesn't provide the same defensive workrate that Alexis/Pedro do. Cuadrado too wouldn't track back much which in total might force us to put in a midfield like Rafinha-Rakitic so that we aren't totally screwed effectively benching Iniesta. It also raises an issue of too many ball carriers in 1 team (Cuadrado, Messi, Neymar, and Suarez all absolutely love dribbling and if we include Rafinha he does too. This is more selfish than even RM since Ronaldo is more poacher than ball carrier while Bale/Di Maria do most of the dribbling).
If we want to fit in all of Messi/Suarez/Neymar into one lineup and make it work, we'd be poking holes everywhere in our system. Suarez's talent is welcomed but I think we'll have to really depend on other players changing their roles to avoid making our side too unbalanced (i.e Neymar becoming more of a defensive workhorse and improving his play on the right side while Iniesta becomes more conservative into a CM role and Rafinha improves enough to be in contention as a starter).