4) Here is an example of scale with 5 minutes resolution, see bold text. To simplify reading I have transformed UTM format to POSIXct,and left the stock values same for all the 3 lines.

1,1|2017-06-19 09:40:00 CEST|1652.05|1652.18|1649.93|1650.18|0
1,1|2017-06-19 09:45:00 CEST|1652.05|1652.18|1649.93|1650.18|0
1,1|2017-06-19 09:50:00 CEST|1652.05|1652.18|1649.93|1650.18|0