Those verses don't contradict a need for receiving the gift. Grace and faith don't negate the action of the will, nor does a passive reception of the gift of salvation negate it being of grace and faith.
As for support of such a need, it's threaded throughout the whole Bible from Joshua presenting the choice to the Israelites to Paul declaring that salvation is for those who confess and believe to the Spirit and the bride saying "Come!" Justification is universally available, but salvation is about more than being justified.
I can agree with you on the one thing. Salvation itself must be worked out on an individual basis. However; initially you are bestowed
with faith and love that come from the fullness of Jesus Christ. That is the election process of God. Whomsoever He bestows those things
upon are the true believers from the heart. Rom 3:22 It's not a gift you have to pick up and say I picked it up therefore I did something
to accept the gift. It is the circumcision of the heart done by the Father. You can't do that nor can you bestow the faith upon yourself.
If you were able to have anything to do with the initial gift of salvation then you would have a right to boast, but that is not the case.
This is what Paul spoke to in 1 Ti 1:13-14 He was a blasphemer etc.. persecuting the Ekklesia and even on his way to arrest more when
his time of visitation came. He at that time was not a believer, but he had heard the gospel, therefore was betrothed whether he knew
that or not, his infilling of faith and love came at the time appointed of the Father. Did he then start to work out his own salvation? Yes
And that comes over much time as we apprehend what we have been apprehended for.
When we are given life to have within ourselves (born of the Spirit) we are empowered to become a son of God. The apprehending
of what needs be done to accomplish that goal is why the Holy Ghost is given as a guide. He is a birth right gift-guide. We can
choose to neglect this gift or we can follow along and be separated from the world religions esp organized Christianity but it will
come with a cost. The groups of today have a set of doctrines that they will defend unto death especially yours, and if you present
what the Holy Ghost has taught you, you will be excommunicated, tossed out, barred form coming back etc.... seen as an outcast.
Why? Because they are deceived and love the praise of men and money, more than the praise of the Father.
Justification unto life was accomplished for you at the cross of Jesus Christ. Rom 5:18 That means that once His faith and love reside
in you, you are born of the spirit, called of God to begin becoming a son. That call and gift is something the Father will never
repent of. Rom 11:29 The issue at hand is now we have one who is born of the Spirit that will never be removed from the Spirit
but must eventually become what he/she was predestined to become-a son. How long that takes is the individual race that each
elect must run. Working it out.