Balanta is available in the first season with Newcastle, and he should be the immediate first buy. You can raise a couple million by the sales of Obertan, Williamson, Elliot and the Ameobis. Don't sell any of your starting 11, they'd all go for much less than you could get for them in a year or two's time.
If you can, by use of negotiation with the board, and re-evaluating season predictions, get 8.5 million after buying Balanta, you could try and get Tello, as left wing is, overall, your weakest area. If you're not playing with a left winger, and you have a bit more in the bank, you could try and go for Volland.
I personally prefer a 4-1-2-2-1 with Newcastle in the first season, with a 4-2-3-1 as a backup tactic for the very easy games, however if you can't get enough to buy other players, a 4-1-2-1-2 or a 5-3-2 will also work, and wont require you to buy anybody else.
Direct passing does not suit Newcastle. Your best striker is Remy, your best midfielder is Ben Arfa and your best defender is Debuchy/Coloccini. None of these players are great in a direct setup. This means, without a complete overhaul, when buying players, you shouldn't buy anyone who is more suited to a direct game, unless they are massively underpriced, or you just need a stop-gap solution.
Newcastle are a fairly easy team to work with.