Primeiro, este erro:

devtools::find_rtools()

WARNING: Rtools 3.3 found on the path at c:/Rtools is not compatible with R 3.2.0. Please download and install Rtools 3.2 from http://cran.r-project.org/bin/windows/Rtools/, remove the incompatible version from your PATH, then run find_rtools().

Mas este não é o único, observem quando se inicia com o rstudio R version 3.2.0 (2015-04-16) -- "Full of Ingredients" Copyright (C) 2015 The R Foundation for Statistical Computing Platform: x86_64-w64-mingw32/x64 (64-bit) R is free software and comes with ABSOLUTELY NO WARRANTY. You are welcome to redistribute it under certain conditions. Type 'license()' or 'licence()' for distribution details. R is a collaborative project with many contributors. Type 'contributors()' for more information and 'citation()' on how to cite R or R packages in publications. Type 'demo()' for some demos, 'help()' for on-line help, or 'help.start()' for an HTML browser interface to help. Type 'q()' to quit R. Error in tools:::httpdPort <= 0L : comparison (4) is possible only for atomic and list types sugestões? ldeassis