Not necessarity. Training is not a prerequisite for undertaking the GCL Certificate exams. If you possess the required knowledge, then you can contact an accredited TC to book the exams directly. Otherwise, you may need to take training courses for the modules in which you need some preparation.
Yes, the accredited TCs are free whether to provide training alone, or exams alone, or combined packages of training and exams. It's advisable to contact more than one TC to get more information about their offerings and what fits you better.
TC Accreditation is meant for Test Centers who are providing GCL exams. If you want to provide training courses only and not planning to provide exams to candidates, then you only need to get your courseware approved, and you don't need to go through the TC accreditation process.
Successful candidates who complete the 4 modules of GCL Certificate will be granted a certificate which will be available online at the GCL website when you search by the candidate e-Index Code number. No printed certificate is posted to candidates from the GCl central office. Accredited TCs can however provide their candidates with printed copies of the online available certificate if they like.