1. The exact names of the php libs depends on your distro. This is my PHP stack on Centos 7:
$ rpm -qa |grep php
php73-mysqlnd-7.3.6-2.el7.ius.x86_64
php73-opcache-7.3.6-2.el7.ius.x86_64
php73-mbstring-7.3.6-2.el7.ius.x86_64
php73-gd-7.3.6-2.el7.ius.x86_64
php-php-gettext-1.0.12-1.el7.noarch
php73-pecl-imagick-3.4.4-2.el7.ius.x86_64
php73-cli-7.3.6-2.el7.ius.x86_64
php73-xml-7.3.6-2.el7.ius.x86_64
php73-json-7.3.6-2.el7.ius.x86_64
phpMyAdmin-4.4.15.10-3.el7.noarch
php73-tidy-7.3.6-2.el7.ius.x86_64
php-pear-Net-Curl-1.2.5-10.el7.noarch
php-tcpdf-dejavu-sans-fonts-6.2.26-1.el7.noarch
php-fedora-autoloader-1.0.0-1.el7.noarch
php73-pdo-7.3.6-2.el7.ius.x86_64
mod_php73-7.3.6-2.el7.ius.x86_64
php73-soap-7.3.6-2.el7.ius.x86_64
php73-process-7.3.6-2.el7.ius.x86_64
php73-common-7.3.6-2.el7.ius.x86_64
php73-bcmath-7.3.6-2.el7.ius.x86_64
php73-devel-7.3.6-2.el7.ius.x86_64
php73-fpm-7.3.6-2.el7.ius.x86_64
php-tcpdf-6.2.26-1.el7.noarch
2. Yes. 7.3 is preferable.