Selenium - where to start the installation?

Question

Parsing

I use Ubuntu 18.04, I rent a virtual machine on digitalocean:
MEMORY: 1 GB
VCPUS: 1 vCPU
TRANSFER: 1 TB
SSD DISK: 25 GB

I want to use Selenium in conjunction with php, for this I chose this library .
At the moment I don't have Desktop.

Question 1: Can anyone give a list of what needs to be installed on Ubuntu to get started with Selenium?
0. Desktop (for Chrome Headless they say it's not necessary, but I have no experience, so it's probably better to install it?)

1. Php-webdriver
2. Selenium Server или Chrome Headless (2-й говорят лучше)
3. Java
4. Браузер Google Chrome
Что-то еще нужно устанавливать?

Question 2: Are these characteristics sufficient? At the same time, there are still scripts on the server that perform curl tasks, phpmyadmin, etc.
Question 3: Is the library compatible with Chrome Headless?

ps Never used Selenium, so sorry in advance for possibly stupid questions.