What objects (files, etc.) should the designer provide based on the results of his work?

Question

Design

Good afternoon!
We are a young group of developers working remotely from each other and from clients. At the moment, everything is very chaotic in our company. We have recently started our activity. In this regard, many questions arise.
At the moment I'm interested in the following. The designer develops the identity, layouts of business cards, forms for reports, envelopes. There are some standards that describe the result of the designer's work in the form of final objects (files and so on). File format, image dimensions and so on?

Answer 1

For printing - png or pdf for viewing, eps with sources as a universal format + you can have the original in .ai (or, God forbid, .cdr). The main idea is that the client himself (with the help of his designers) can print more business cards for other people, change the address on the envelope, or even make a new design based on the old one.
Accordingly, everything that went into work, everything is provided. No intermediate options are provided in any form, because they belong only to you.

Answer 2

Another important point that everyone always forgets is FONTS! Be sure to transfer the fonts, because the customer will not be able to change the address on the envelope without the font (or the style will be lost).
In the print version, all fonts must be converted to curves, but remain text layers in the source files.

Answer 3

Depending on how you plan to work with the client in the future: if this is your constant, and you fully support it, then there is no point in giving the source code, if it is a one-time client, then you can safely give everything completely: fonts, vector layouts, if you do it in a vector ( I give the full source code, because the printing houses are different, the client's situations are different, and I don't like it when they pull me with "change phone").
Those. sources (I give ai\psd and PDF, fonts, linked illustrations, cover letter (with a description of what it is and what each file is), + necessarily (!!!) previews in jeeps.