Regarding your query of Master/Slave database replication, Yes absolutely possible, the deliberate delay is specified in time (means slave will lag behind master by at least this time) and default value is 0 seconds, so you can safely set it to hours, even days. This feature of delayed replication is available from MySQL 5.6 and onwards, I dont think 5.5 and earlier have this feature.
regarding creating a redundant Moodle architecture (not talking about high availability), just creating a replication on database wont do the job, as you may have images uploaded and these images goes into moodledata folder and links go to database, so essentially you'll have links to uploaded files intact, but no files to show on shadow copy of Moodle unless you copy over the contents of the moodledata folder to shadow copy server.
With that being said, as there is a delay of 24 hours, you can safely copy the contents of moodledata folder manually on to your other server every 24 hours (which makes sense to me as you dont need realtime update of the contents). as its just moodledata folder and database that actually gets changed everytime, whilst moodle files folder remains intact all the time (apart from installing plugins etc).
This above solution will be easier to setup (considering the delay you required), else setting up an instant updates on shadow server requires more than that, which in case if you are on a windows based server setup, I can assist, else Emma is way more competent in Linux and LAMP setup than I am.