There are some Projects to implement a FAT to an AVR Microcontroller in the Internet.
I've done that with an ATMEGA 32 Controller that writes the incoming serial Data onto an SD Card.
Logging starts by set the logging connector to +5V.
The maximum size of the SD storage is 1GB. Bigger Space affords a cluster size of 1kB - Too much for an AVR Controller!
To split the logging Part from the Store Part has the advantage to get more flexibility.
And you can use the serial TxD line from Controller additional, to serve an USB serial Converter like the FT232RL or an RS232 Level Shifter ( e.g. MAX232 ) for Live logging.
And the debugging would be easier, because you can test both with an simple serial connection to PC.
The next Problem is the Power Source. Most Displays need 5V Supply Voltage. An SD Card only works with 3,3V.
SD Card and Display can only work with "tricks" ( resitor voltage divider ) at the same Controller.
Touch Displays are often very expensive. A Dotmatrix Display and normal Tast's are much cheaper 2x16 Character costs 5,-Euros.
A graphical Display with 128x64 pix you can get for 18,-Euros. A Touch Display will cost you more than 100,-Euros.
Look first for a cheap Touch Display and an suitable library for the Controller, before start the Project.
As Humidity / Temperature Sensor you can use one of the SHT... Series from
Sensirion AG
With PH Sensors i have no experience - sorry.