1. That is not called anything in the webhosting terms. All you need to run XOOPS with an arbitrary amount of XOOPS users is a MySQL database and 5 MB of space on the webserver.

If you want to have more modules, images, this and that, then you'd need more space, but 20 MB is usually enough - 100+ and you should be having no space problems at all

2. Data transfer is a maximum of what your site MAY use - bandwith is how fast it can go.
e.g. 15 GB a month is what some hosts allow. If your average page is 150 KB, then you can have roughly 100,000 page hits per month.
Bandwith is how fast each page is loading. If 20 people are on your site and load a page at the same time and each have a download bandwith of 256 Kbit/s, then for each visitor to feel that it is fast, the server will need a 5 Mbit connection (there are some packet-efficiency making it less straight forward, but let's just go with this example) to serve the visitors.

Usually good webhosting companies have a big enough bandwith to serve your visitors fast enough - but if you have large pages with lots of images or host files to download, 15 GB can easily be used.

Something else to keep in mind about CPanel if you are a gamer. Your ISP host is only going to open the ports that are required for CPanel to operate. They are:

Ports that must be open to run cPanel behind a firewall:

20 ftp tcp inbound/outbound

21 ftp tcp,udp inbound/outbound

22 ssh tcp inbound

25 smtp tcp inbound/outbound

26 smtp tcp inbound/outbound

37 rdate tcp outbound

43 whois tcp outbound

53 DNS tcp/udp inbound/outbound
(inbound is only needed if you run your own public DNS server you)

80 http tcp inbound/outbound

110 pop3 tcp inbound

113 ident tcp outbound

143 imap4 tcp inbound

443 https tcp inbound

465 smtp tls/ssl tcp/udp inbound/outbound

873 rsync tcp/udp outbound

993 imap4 ssl tcp inbound

995 pop3 ssl tcp inbound

2082 cpanel tcp inbound

2083 cpanel ssl tcp inbound

2086 whm tcp inbound

2087 whm ssl tcp inbound

2089 cp licence tcp outbound

2095 Webmail tcp inbound

2096 Webmail SSL tcp inbound

3306 MySQL tcp (only if you need to connect remotely)

6666 chat tcp inbound

If you are want to show a live server stats program on your webpage, and your server port is XXX.XXX.XXX.XXX:7777 or something like XXX.XXX.XXX.XXX:27960 It won't display on your webpage.

If you ask your ISP host to open other ports, they will normaly tell you that for security reasons we only open the ports required for CPanel to operate.

In order to get your live server stats program to work, you would need to hack your game server reporting port to an open port.