Thanks for writing. Your questions and story indicate some misunderstandings. I have written about it several times in the past couple of years. Please check out posts with tags like "non-canonical vs illegal" or various references to non-canonical. If that is not helpful to you, then please come back to me and I will write about it again with your questions in mind. Let me just say you can remain a Catholic and live as a hermit apart from c 603. What you cannot do is claim to be a Catholic Hermit, that is, a hermit living this life in the name of the Church. You will be a Catholic AND a hermit, but not a Catholic hermit.
Regarding formation that c 603 shows the need for significant formation proior to beginning a mutual discernment process with your diocese. This is true about the history of the canon and the situation out of which Bp Remi de Roo was caused to make an intervention at Vatican II, and it is true when one reads the canon itself. I say this, not because it speaks of formation, but because it does not. Instead, it assumes this and, moreover, it assumes that one understands the constitutive elements of the canon "from the inside out". It also assumes one can write a liveable Rule, something that takes sufficient lived experience of the eremitical life and of life leading to it. Finally, c 603 requires that one petition to be professed and consecrated, a petition that really indicates a life-choice where one affirms that God calls one in this way and no other to become a whole and holy human being who abides in God and allows God to abide in her.
Canon 603, which is normative for solitary hermit life, is not for beginners. Neither is it for young persons. Instead, it assumes a great deal of the individual petitioning a diocese for this specific standing in the Church. If you have read the post I put up on the three-stranded braid, you will have noticed I spoke of this as an ecclesial vocation, one that required a strong sense of this dimension of the vocation. I will tell you that that takes a significant time and some study to be able to develop. Again, this vocation is not an "entry level" vocation. It presumes age, experience (including strong relationships with others), theological expertise, ecclesial commitment and sensibilities, and some really positive reasons as to why one feels called to this vocation and no other, especially given how difficult it is to achieve human wholeness in eremitical solitude; most people only come to wholeness with regard to significant experience in community of all sorts.
Since you have not lived as a hermit before this, the first thing you need to do is get yourself a good spiritual director. Work with them regularly for a couple of years and see how that goes. See if you really still feel called solitude. See also if you feel called to contemplative prayer or living as a contemplative. If, over several years, these things come together for you, begin planning on a way to support yourself in solitude and then embrace solitude experimentally. Find ways to study eremitical life, the elements of the canon (including the evangelical counsels), and strengthen your relationship with the Church. Throughout all of this, pay attention to the way God is present and works in your life. With your director, find ways to attend to those with greater and greater fidelity; develop your prayer life so this is primary for who you are. If you do all of this and conclude that you are coming to greater wholeness and holiness in eremitical solitude, in five or seven years you can check in with your diocese and explain what you have done while seeking their feedback on petitioning for admission to profession (and eventual consecration) under c 603.As a Catholic lay person in the Church, your are completely free to live almost any way you want in the lay state. That includes living as a hermit, though it would be as a non-canonical (non-normative) hermit. This is a good way of discerning whether you are called to live hermit life in law. For admission to the consecrated state, only the Church can receive you in this way. That requires a process of mutual discernment where both you and the diocese discerns God's will in this regard.

