You will find the technical specifications for the IIci, with the supported operating systems,
here.
A full System 7.5.3 is available for download from Apple (e.g. a
British and a
US version).
The 68030 processor means that a text-based web browser (such as
WannaBe) is the only realistic option. Email, via an older version of Eudora Light, will be fine too. As Miles has indicated, a modem can be connected (you will need something like MacPPP 2.5.3
here for the connection, if System 7.5.3 is used). Alternatively, a separately installed Ethernet card would allow the computer to be attached to a network.
For older software, have a look (for instance)
here. A free word processor can be found
here.
It would be a good idea to check the internal battery (see, for example,
this page).
Jan