As for the dependencies: If they and the application itself are available through apt-get then dependencies are automatically resolved, there's no need for (or help in) installing them explictly and separately.
If the application doesn't install then that's because of conflicting dependencies, e.g. app A depends on lib L version n (and _only_ n or <=n), app B depends on lib L version m (and can't use e.g. n). Then you will only be able to install either A or B, not both.