SSL certificate on Multisite

Hi,
On an existing Multisite install I would like to install a SSL Certificate. I have read https://premium.wpmudev.org/blog/ssl-domain-mapping/ but just to make shure I am thinking right I have the following questions.

On this multisite I am using the domainmapping plug-in https://wordpress.org/plugins/wordpress-mu-domain-mapping/. This plugin hasn’t been updated in two years so I think it’s better to install your plugin: https://premium.wpmudev.org/project/domain-mapping/
Will it be a problem to just uninstall the old plugin and install and configure your plugin? Or should I do this differently?

I understand for a Multisite installation with multiple domainnames on wildcard I will need an Wildcard SSL cerftificate and then https can be configured?

Thanks in advance,
Ariane