Bolaven Plateau is in Southern Laos.
Minimal English is spoken. Usually one fluent English speaker can be found at banks. Even guesthouse are limited in english.
In Pakse, you can rent a motorbike for about $15 for two days. Leave before the sun gets too hot and head towards Tad Lo. Stop for lunch and at other water falls along the way. Once at Tad Lo you can find a place to sleep at any one of the many guesthouses. The next day continue to Pakxong where you can get some coffee and then head back to Pakse.
from Pakse, go to Dao Heung market (~8k Kip by samlor), take bus to Paksong (first 9am, ~20k Kip). After about 1h30, stop at km38 for That Fane / Tham Cham pee crossing (big board advertising the falls). You need to walk about 1 and 1.8km for each one Entrance fee for each fall: 5k Kip From there, walk/hitchhike/catch a bus to km40 for Yuang fall. probably the best of three: hotel and stalls nearby. You can also go just in front of the waterfall to see a permanent rainbow at your feets but be prepared for a shower ! After hitchhike/catch a bus to reach Paksong.
From Paksong, watch the road to catch a transport/bus to Tha Theng (for example Pakse-Attapeu). Be aware that it seems there is no such a bus between 2pm and 4pm. Bus Pakse-Attapeu to Tha Theng costs about 25,000 Kip. Tha Theng bus station is at market level, small hut near the road. If you arrive at Tha Theng after 4pm, it seems there is no transport at all to Ban Beng / Tad Lo except paying a costly motorbike (could be asked for 150,000 Kip ...). In this case, better to take a night there.
From Tha Theng, songthaew to Pakse is about 30k Kip (starting at about 7.30am) and to Ban Beng about 20k Kip (starting at about 8am, about a hour). Between Ban Beng and Tad Lo, test your luck and walk/hitchhike/catch a bus either to Tad Lo or crossing with main road.
At Tad Lo, you could see Tad Hang and Tad Lo waterfalls.
Bus to Pakse are taken from crossing and seems about every one hour during day (~30k Kip, 2h, to southern bus station)