HLM - non-linear IV and placement of individual characteristics in the model

Hi all! I am working on my dissertation and run across a couple of questions when structuring HLM model. The data looks as follows:
I conducted an experiment among 300 participants with 2x3 design, where each individual was assigned to one of the two conditions and within condition answered to the questions about three issues.
Questions I have before creating and testing the model::confused:
1. can I use "issue" variable in the same way as scholars use time variable in longitudinal studies? I.e. usually in studies you have 3 measures for t1, t2, and t3 (continuous variable). I have three issues instead of time periods (categorical variables) that do not necessarily follow linear pattern, meaning that response to issue 3 is not necessarily higher on likert scale than response to issue 2 or issue 1. I suspect it should not matter whether it's time or issue, but I just want to be sure I am not violating any assumptions I might have forgotten or overlooked.
2. I also measured individual characteristics of participants and want to use them in order to explain their responses to issues within conditions. Will I enter these characteristics at the 1st or the 2nd level?
Thank you so much in advance for your time and for your help to a novice in this forum - I greatly appreciate it!:)