Falcao on loan is an option to pressure Diego Costa to perform in his as the first striker. If not Falcao, I would rather keep Remy and promote Bamford as the 3rd striker.
A better alternative to Nainggolan is Morgan Schneiderlin who more imposing physically and can play with some technique too as well as being EPL proven. Also, he's keen on a move out of Southampton. Him coming would not be as a mere squad player (we have enough of those i.e. Mikel, Ramires and Loftus-Cheek) but would present himself as a legitimate challenger for a first team spot.
Why sign Alderweireld as a mere squad player whom I think would find it difficult to fill in the boots of John Terry or Gary Cahill if they are injured or suspended? I hope Mourinho lands his favourite Rapahel Varane who can play alongisde Terry and be his successor when he hangs up his boots.
In short, the club should go for first team challengers as Mourinho stated rather than players being contended to sit on the bench and just collect their paychecks.