(1) Dominating but no goals and conceding problems - Well, I take it as spurs, you alreay have a decent keeper. Maybe the thing to look into would be better strikers with better finishing ability. Sorbis, Baracite are options you can look into. Baracite being the cheaper of the two.
(2) Giving away balls in dangerous areas - Might want to look at how your defenders distribute the ball as well. Also, look out for problem defenders which tend to dally on the ball. Sell them a.s.a.p. in my view.
(3) Generally, hike up the slider so that the team does not play a short passing game as this means the ball is up in the air more often.

But mix this up a bit to suit the opposition.
Hope this helps.